
    352 F. 2d 539
    JOE ROBERTSON AND ADDRUE ROBERTSON v. THE UNITED STATES
    [No. 393-62.
    Decided November 12, 1965]
    
      
      Reuel W. Little, attorney of record, for plaintiffs.
    
      David D. Hochstein, with whom was Assistant Attorney General Edwin L. Weisl, Jr., for defendant.
    Before Laramore, Acting Chief Judge, Durfee, Davis and Collins, Judges and Whitaker, Senior Judge.
    
   Per Curiam:

This case was referred pursuant to Rule 57(a) to Trial Commissioner Wilson Cowen (now Chief Judge Cowen), with directions to make findings of fact and recommendation for conclusions of law. The commissioner has done so in an opinion and report filed on May 28, 1964. The plaintiffs have excepted to the opinion and certain of the findings of fact. The parties have filed briefs and the case has been submitted to the court without argument of counsel. The court agrees with the commissioner’s findings, his opinion and his recommended conclusion of law, as hereinafter set forth, and hereby adopts the same as the basis ‘for its judgment in this case. Plaintiffs are therefore not entitled to recover and the petition is dismissed.

OPINION OB THE COMMISSIONER

This action was brought on December 11,1962, to recover compensation of $47,000, representing the claimed diminution in value of plaintiffs’ property in Grayson County, Texas, because of the alleged taking of an avigation easement caused by low and frequent flights of military jet aircraft operating from Perrin Air Force Base, Sherman, Texas.

The evidence shows that the Government has taken an avigation easement over plaintiffs’ land, and the defendant has admitted this in its brief. However, the defendant contends that the taking occurred more than 6 years prior to the filing of plaintiffs’ petition on December 11, 1962. Thus, the primary issue for decision is whether the claim is barred by the statute of limitations, 28 U.S.C. § 2501. The actual issue is whether a new cause of action accrued in 1960 with the advent of F-102 jet aircraft at the base, from which the T-33 and F-86 fighter jets had been operating since 1953.

Perrin Air Force Base is located 10 miles north of Sherman, Texas, and, on July 17, 1952, was designated a permanent base. The base was used exclusively by propeller-driven aircraft until December 19, 1952, when the first jet-propelled aircraft were delivered. In February 1953, the first class of students began training in the flight of jet aircraft.

With the inception of jet aircraft operations at the base, it was necessary to construct two new runways of greater length. The first of these, known as the east North-South runway, was built in 1952 and is located about 1,000 feet west of the original north-south triangular runways that were used by propeller-driven planes. As the volume of jet air traffic increased, a new westerly North-South jet runway was completed in December 1953, and in January 1954, its use by jet aircraft commenced. The center line of this runway is parallel to and 1,000 feet west of the center line of the easterly North-South runway.

Both the easterly and westerly runways were 8,000 feet long until November 1962, when the easterly runway was extended 1,000 feet to the south. The easterly runway, the only jet runway until January 1954, was used for approximately 67 percent of the takeoffs and landings because the ground control approach equipment at the base could be used only on this runway. The easterly runway is also used more than the westerly runway because it is nearer to the hangars and other installations.

Plaintiffs’ property is divided into two tracts, both of which are located in a noncongested area as defined by the Civil Aeronautics Authority [now the Federal Aviation Agency]. Tract A, which comprises 315 acres, is used primarily as pastureland for the grazing of cattle, but there are also six producing oil wells on the land. From 1953 to the present, the highest and best use of this land has been for the grazing of livestock and the production of oil. The north boundary line of the tract is 2,400 feet south of the south end of the east North-South runway as extended, and the major portion of the tract is located within the approach zone to and take-off zone from this runway. Tract B is located approximately one-quarter of a mile southwest of Tract A. It is plaintiffs’ home place, and, as shown in the findings of fact, is a well improved piece of property with a centrally heated and air-conditioned frame residence, tenant house, windmill, storage tanks, a shop, a barn, and several stock tanks. Seventy acres of the tract are used for the production of small grains and the remainder is pastureland. Since 1953, the highest and best use of this tract has been as an owner-operated stock farm. The north boundary line of Tract B is 7,350 feet south of the south end of the west North-South runway, and the residence is 8,410 feet from the end of that runway. The maj or portion of the tract is located within the approach zone to and the take-off zone from the west North-South runway.

There is no evidence in the record tending to show that the propeller-driven aircraft operating from Perrin Air Force Base prior to 1953 interfered substantially with the use and enjoyment of plaintiffs’ land. Therefore, flights of such aircraft will be disregarded for the purposes of this action.

The major types of jet aircraft which have operated from Perrin Air Force Base in substantial numbers since 1953 are the T-33 Jet Trainer, the F-86 Sabre Jet, and the F-102 Delta Dagger. All three aircraft are single-engine, jet-powered, fighter planes, which are extremely noisy when taking off from the runways because at such times they operate at full military power. The T-33 weighs 15,000 pounds and is not equipped with an afterburner; the Sabre Jet weighs 19,725 pounds and is equipped with an afterburner; and the F-102 weighs 31,560 pounds and is also equipped with an afterburner. The noise, vibration, and disturbance created by low overflights of the F-86 and the F-102 are considerably greater than that generated by the Jet Trainer. The F-102 is larger and more powerful than the F-86, has better performance with greater maneuverability, a shorter take-off roll, and a dramatically more rapid rate of climb.

The Jet Trainers have operated continuously at the base since February 1953, and the F-86 was used there in substantial numbers between February 1953 and June 1962. In May 1960, F-102 jet fighters were first assigned to Perrin and gradually replaced the F-86’s, which were not used after June 1962.

The traffic pattern at Perrin Air Force Base has remained the same for the past 10 years, and flight regulations there require a jet on takeoff to climb to an altitude of 500 feet above the ground before executing a mandatory turn to the east or west.

The direction in which takeoffs or landings are made at the base depends upon the direction of the prevailing winds and a 10-year study of the wind there indicates that more than 70 percent of the takeoffs were made toward the south over or in the direction of plaintiffs’ property, and about 30 percent of the landings were made toward the north over plaintiffs’ property.

On an average day at the base and under normal operating conditions, the T-33 has a take-off roll of about 4,000 feet; the F-86, with afterburner, has a take-off roll of approximately 5,000 feet; and the F-102, with the use of an afterburner, has a take-off roll of 3,000 feet before becoming airborne. In the majority of takeoffs made to the south over plaintiffs’ property, the T-33’s and F-86’s passed over plaintiffs’ property at a height of from 200 to 300 feet above the terrain. On the other hand, the F-102, with its shorter takeoff roll and more rapid rate of climb, usually reaches an altitude of 800 feet above the ground before passing over Tract A, and from 1,200 feet above the terrain when passing over Tract B on takeoffs toward the south. Normally and on most occasions, the F-102 attains an altitude of more than 500 feet before it reaches Tract B on takeoffs toward the south, will make a 30-degree turn to the right and will not pass over any part of Tract B. The operation of jet aircraft, particularly the F-86 and the F-102 planes, is affected by weather conditions and by pilot technique. On extremely hot days and on infrequent occasions, both the F-86 and F-102 pass over plaintiffs’ Tract B at lower altitudes than indicated above.

The noise and disturbance created by the three types of jets when flying over or near plaintiffs’ property while landing toward the north was considerably less than the noise made on takeoffs because the aircraft always land under reduced power and without using afterburners. Since the F-102 has a steeper glide path for the final approach to the runway than either the Jet Trainer or the Sabre Jet, it passes over plaintiffs’ land prior to landing at lower altitudes than either of the other two aircraft when the visual flying rules are used aiid is, therefore, somewhat noisier. When the radar ground control approach is used in landing, all three aircraft pass over plaintiffs’ property at an average altitude of approximately 375 feet.

During 1953 and 1954, the volume of air traffic at Perrin Air Force Base was as much as 14,000 landings and takeoffs within a month, including low approaches, and as many as 40 “touch-and-go” maneuvers per day. Since 1955, there have been approximately 700 to 750 jet operations per day during the normal flight schedule, which occurs between the hours of 8:00 A.M. and midnight on Monday through Friday. The training schedule consists of 20 working days a month, there being little flying activity on Saturdays, Sundays and holidays.

In an effort to meet defendant’s affirmative defense that the claim is barred by the statute of limitations, plaintiffs contend that defendant did not take an avigation easement by virtue of the overflights of the T-33’s and F-86’s and that the statute did not begin to run until after May 1960, when the F-102’s were used in substantial numbers. In the alternative, plaintiffs assert that the low flights over plaintiffs’ property by the T-33’s and F-86’s amounted only to a partial taking and that they are entitled to compensation for the additional taking after the F-102’s began regular flights over their property at low altitudes.

It is clear from the record that there is a substantial difference in the noise and disturbance caused by the flights of T-33’s as compared with those of the F-88’s and the F-102’s, and it may be concluded that the overflights of the Jet Trainers did not constitute a taking of an avigation easement over plaintiffs’ property. However, the greater weight of the evidence shows that there were numerous, regular and frequent takeoffs of F-86’s with the afterburners in use over plaintiffs’ property at altitudes well below 500 feet above the ground in the period from February 1953 to December 11,1956. These regular and frequent intrusions into the air space above plaintiffs’ land interfered seriously and substantially with the use and enjoyment of such lands for some time prior to December 11,1956.

The record contains no scientific data from which a comparison can be made of the noise intensities of the F-88 and the F-102 during takeoff with afterburners on. Although there is some evidence to the contrary, the greater weight of the evidence shows that the noise and disturbance created by the F-86 and the F-102 on takeoffs is so loud and disturbing that the human ear can barely distinguish any difference in the intensity of the sound created by these aircraft when flying over plaintiffs’ land at low altitudes.

From the above recitation of facts and from the more detailed findings of fact, the following conclusions are evident:

(1) The frequency of flights by jet aircraft at Perrin Air Force Base over plaintiffs’ property at altitudes below 500 feet was not increased by the phasing out of the F-86 and its gradual replacement by the F-102.

(2) The most substantial and serious interference with the use and enjoyment of plaintiffs’ property occurred while jet aircraft were taking off toward the south over plaintiffs’ property with afterburners engaged. Since the F-102 consistently achieved a substantially higher altitude on takeoffs over plaintiffs’ property than the F-86, takeoffs of the F-102’s over such property at altitudes below 500 feet occurred only irregularly and infrequently. Plaintiffs have not shown by a preponderance of the evidence that the interference with the use and enjoyment of their property was increased to any significant extent when the F-102 type of aircraft began flying in substantial numbers at the base or that the value of their property was further diminished as a direct result of such low overflights of the F-102 jets.

(3) The regular and frequent takeoffs of F-86 jets with afterburners in use over plaintiffs’ lands at altitudes below 500 feet constituted a direct and immediate interference with the enjoyment and use of plaintiffs’ lands for at least a year before December 11,1956, the beginning of the 6-year period preceding the filing of the petition. Brin v. United States, 159 Ct. Cl. 332, (1962). Cf. Bacon v. United States, 155 Ct. Cl. 441, 295 F. 2d 936 (1961).

This court has previously held that flights of the F-86, with such regularity and frequency as in this case, resulted in the taking of an avigation easement over the property involved in the particular case. Wilson v. United States, 151 Ct. Cl. 271 (1960); Wright v. United States, 150 Ct. Cl. 386, 279 F. 2d 517 (1960); Matson v. United States, 145 Ct. Cl. 225, 171 F. Supp. 283 (1959). In Matson, in which the facts were quite similar to the case at bar, F-86’s began operating from the air base in August 1953, the F-102’s being assigned to the base 3 years later. The court held that the taking occurred in August 1953, when regular and frequent flights of the F-86 occurred.

By declarations of taking filed, respectively, on December' 31, 1954, and June 7, 1962, in the United States District Court for the Eastern District of Texas, the United States took clearance easements over Tracts A and B which gave the Government the right to clear and keep clear of obstructions the air space above the glide angle plane extending southerly from the air base over those portions of plaintiffs’ tracts lying within the approach zones to the two runways. The glide angle plane covered by these clearance easements ranged from 18 to 70 feet above ground level. Plaintiffs point to these clearance easements and argue that the Government’s action in obtaining them indicated its intention to lower the flight angle and thus to fly its planes over plaintiffs’ property at lower altitudes. Plaintiffs’ conclusion does not necessarily follow, there being a distinction between the altitudes delineated by the clearance easement and the flight angle normally used. The clearance easement (sometimes called the glide angle) is not the angle at which planes normally approach the runway, but is the lowest possible angle at which aircraft can fly in approaching the runway; it is the minimum angle of approach consistent with any degree of safety. Dick v. United States, 144 Ct. Cl. 424, 169 F. Supp. 491 (1959); Highland Park, Inc. v. United States, 142 Ct. Cl. 269, 161 F. Supp. 597 (1958); Herring v. United States, 142 Ct. Cl. 695, 162 F. Supp. 769 (1958). The difference between the minimum glide angle described in the clearance easement and the normal glide slope can be attributed to a safety margin designed to provide for emergencies.

Although the taking of the clearance easements reduced the value of plaintiffs’ property, plaintiffs have been compensated for such damage in the condemnation proceedings.

From what has been said above, it follows that the defendant had taken an avigation easement for the flight of its aircraft over plaintiffs’ property at altitudes below 500 feet more than 6 years prior to December 11, 1962, the date the petition was filed, and that plaintiffs’ claim is barred by 28 U.S.C. 2501.

FINDINGS or Fact

1. This petition was filed December 11, 1962, to recover compensation of $47,000, representing the diminution in value of the plaintiffs’ property in Grayson County, Texas. Plaintiffs allege that such reduction in value was caused by low and frequent flights of military jet aircraft operating from Perrin Air Force Base, Sherman, Texas.

2. Perrin Air Force Base, which is located 10 miles north of Sherman, Texas, was originally acquired by the United States from Grayson County, Texas, under deed dated Jan-nary 23,1950. On July 17, 1952, Perrin Air Force Base was designated as a permanent base by the then Secretary of War under authority of 10 U.S.C. 9773. The base was used exclusively by propeller-driven aircraft until December 19, 1952, when the first jet-propelled aircraft were delivered. In February 1953, the first class of students began training in the flight of jet aircraft.

3. With the inception of jet aircraft operations at the base, it was necessary to construct new runways of greater length. The first of these, known as the east North-South runway, was built in 1952 and is located about 1,000 feet west of the original north-south triangular runways that were used by propeller-driven planes and now serve as taxiways. As the volume of jet air traffic increased, a new westerly North-South jet runway was completed in December of 1953, and in January 1954- its use by jet aircraft was commenced. The center line of this runway is parallel to and 1,000 feet west of the center line of the easterly North-South runway.

4. The jet aircraft which operated at Perrin Air Force Base during 1953 and 1954 were T-33’s and F-86D’s and L’s. The F-86’s are equipped with afterburners; the T-33’s are not. Approximately 50 percent of the flights from Perrin in those years were made in T-33’s, and in about 70 percent of the takeoffs by F-86’s the afterburner was used. The volume of the noise and vibration generated by the operation of these planes is considerably greater than that caused by propeller-driven aircraft.

5. During 1953 and 1954 the normal schedule for the flying of jet aircraft at Perrin was between the hours of 8 a.m. and midnight, Monday through Friday, operations usually being reduced on weekends. The easterly North-South runway, the only jet runway until January 1954, was used for approximately 67 percent of the takeoffs and landings because the ground control approach equipment at the base could be used only on this runway, many of the flights being made for training in ground control approach. The easterly North-South runway is also used more than the westerly runway because it is nearer to the hangars and other installations than the westerly runway, and use of the easterly runway reduces taxiing distance and time. Both the easterly and the westerly runways were 8,000 feet long until November 1962, when the easterly runway was extended 1,000 feet to the south.

6. During 1953 and 1954 when jet aircraft began to operate from Perrin Air Force Base in substantial numbers, the volume of traffic was as much as 14,000 landings and takeoffs within a single month. The direction of takeoff and landing depends upon the direction and velocity of the wind, but the greater number of takeoffs were made in a southerly direction.

7. In addition to the regular takeoffs and landings at Perrin in 1953 and 1954, student pilots were also trained in the “touch-and-go” operation, a. term used to designate a practice landing in which the pilot merely touches the jet on the runway, immediately takes off, and then brings the plane around for another approach to the runway. This procedure is also used in cases where a pilot misjudges his approach to the extent that a landing brings the plane too near the end of the runway. In such situations the ground control officer signals the pilot to take off immediately and to make another approach. The “touch-and-go” maneuver permits the jet to make a sharper turn after touching down than during a normal takeoff, because 60 percent of the engine power is held in reserve for a quick takeoff. The “touch- and-go” maneuvers are part of the regular training at Perrin and occur with as much frequency as 40 times per day.

8. The plaintiffs, husband and wife, are and at all material times have been the owners of 470.5 acres of land in Grayson County, Texas, in the immediate vicinity of Perrin Air Force Base, located south of the two jet runways. The plaintiffs’ property is divided into two tracts of land about a quarter of a mile apart, one of which comprises 315 acres and the other 155.5 acres. For convenience, the two parcels have been designated as Tract A and B, respectively,

Tract A (315 acres) is primarily pastureland used for the grazing of cattle raised by the plaintiffs. There are six producing oil wells on this tract from which the plaintiffs have received royalties of more than $100,000 from the beginning of 1956 through September 4,1963. From 1953 to the present time the highest and best use of this land has been for the grazing of livestock and the production of oil. The north boundary line of this tract is 2,400 feet south of the south end of the east North-South runway, as extended.

Tract B (155.5 acres) is located approximately one-quarter of a mile southwest of Tract A. The main improvements on this property are: plaintiffs’ residence, a tenant house, windmill, storage tanks, shop, barn, and several stock tanks. The residence itself is of frame construction and has three bedrooms, two baths, living room, den, and dining room, and is centrally heated and air-conditioned. The property is fenced, has a blacktop road leading past the residence to the storage tanks, and also has corrals for cattle. Seventy acres of this tract are used for raising small grains such as wheat, oats and barley, and the remainder is pastureland. The north boundary line of Tract B is 7,350 feet south of the south end of the west North-South runway and the residence is an additional 1,060 feet south of the north boundary line, or 8,410 feet from the end of the runway. Since 1953 to the present, the highest and best use of Tract B has been as an owner-operated stock farm.

9. Substantially all of Tract A is located within the approach zone to the east North-South runway and a small portion of the tract on the western side is located within the approach zone of the west North-South runway. Normally, all jet aircraft follow the center lines of the runways on takeoff, and thus Tract A is located within the take-off zone from the east North-South runway for planes taking off toward the south. All of Tract B, except approximately the western one-third thereof, is located within the approach zone of the west North-South runway, and an area comprising approximately the eastern one-third of the tract is located within the approach zone of the east North-South runway. Tract B is located within the take-off zone from the west North-South runway for planes taking off toward the south.

10. The land involved in this case is a “noncongested” area as defined by the Civil Aeronautics Authority, and any citizen has a public right of freedom of transit in the navigable air space above 500 feet of terrain clearance.

11. The two tracts of land have been operated by the plaintiffs for the past several years as a unit for raising mother cows. Plaintiffs have about 70 bead of cattle from which they produce about 65 calves a year. The calves are raised on plaintiffs’ land until they reach a weight of 500 to 550 pounds, when they are marketed to bring from 20 to 28 cents a pound. The plaintiffs have not claimed that the jet aircraft operations at Perrin interfered with their farming and cattle raising activities at any time between 1952 and 1963.

12. In Civil Action Nos. 1054 and 1493 in the United States District Court for the Eastern District of Texas, Sherman Division, the United States by declarations of taking filed December 31, 1954, and June 7, 1982, respectively, took clearance easements over Tracts A and B. These easements gave the Government the right to clear and to keep clear of obstructions the airspace above the glide angle plane extending southerly from Perrin Air Force Base over those portions of tire two tracts of land lying within the approach zones to the two North-South runways.

Because of the rolling character and terrain of Tracts A and B, the ground elevations vary considerably. The glide angle plane for clearance easement purposes over that portion of Tract A within the approach zone to the east North-South runway is 41 feet at the northwest corner, 22 feet at the southwest corner, 22 feet at the northeast comer, and 42 feet at the southwest corner. The glide angle plane for clearance easement purposes over that portion of Tract B within the approach zone to the west North-South runway is 18 feet at the northeast comer, 28 feet at the northwest corner, 70 feet at the southwest corner, and 58 feet at the southeast comer.

As a result of Civil Actions Nos. 1054 and 1493, plaintiffs have received $25,504.25 as compensation for the taking of the clearance easements over their property. At the time of the trial the total amount of compensation for the taking of clearance easements in Civil Action No. 1493 had not been determined, but the record indicates that an additional balance of $965 was due to be paid plaintiffs.'

13. The major types of jet aircraft which have operated from Perrin Air Force Base in substantial number since 1953 are: the T-3B Jet Trainer, the F-86 Sabre Jet, and the F-102 Delta Dagger. The T-33 weighs 15,000 pounds with a full fuel load, and is not equipped with an afterburner. The F-86D and L Sabre Jets weigh 19,725 pounds with a full fuel load, and both are equipped with afterburners. The F-102 weighs 31,560 pounds with a full fuel load and is equipped with an afterburner.

The T-33 Jet Trainers have operated continuously from Perrin since February 1953. The F-86 was used in substantial numbers between February 1953 and June 1962. In May 1960, F-102 jet fighters were assigned to Perrin for advanced training purposes and gradually replaced the F-86’s, which were not used after June 1962. The F-102 is larger and more powerful than the F-86, has better performance because of greater maneuverability, and has a shorter take-off roll with a significantly more rapid rate of climb.

14. The volume of aircraft activity at Perrin Air Force Base has been compiled by the use of a semi-automatic counting device which numbers one count for each landing, takeoff, low approach, and two counts for a “touch-and-go” landing. In a low approach the wheels of the aircraft are brought within a foot or two of the ground, but do not touch the runway.

The parties have stipulated that in 1953 and 1954 there were as many as 14,000 landings and takeoffs at the air base in a single month.

Statistical data compiled at Perrin from May 1955 through May 1963 shows the following traffic count, summarized here:

May 1, 1956 to December 31,1956 (20 months)_ 281, 922
January 1, 1957, to December 31, 1957_ 172,153,
January 1, 1958, to December 31, 1958- 221, 094
January 1, 1959, to December 31, 1959- 193, 839
January 1, 1960, to December 31, 1960_161, 836
January 1, 1961, to December 31, 1961_ 183, 724
January 1, 1982, to December 31, 1962_ 176, 520
January 1, 1963, to May 31, 1963 (5 months)_ 77,614

It is established from the above data that from May 1955 through May 1963 there have been approximately 14,000 to 16,000 jet operations a month at Perrin, including takeoffs, landings, “touch-and-go” maneuvers and low approaches. A breakdown of these figures shows that there were approximately 700 to 750 jet operations a day, based on a training schedule ox 20 working days a month, there being little flying activity at the base on Saturdays, Sundays and holidays.

15. A 10-year weather study at Perrin Air Force Base for the period 1953 through 1962 shows the following percentages for wind average directions during that period of time:

Wind from the north — 29.8 % of the time
Wind from the south — 59.7% of the time
Wind from the east or west — 5.7% of the time
Calm — 4.8% of the time

When the winds were from the south, east or west, or when it was calm, aircraft from the field took off from the south over or in the direction of plaintiffs’ property. The study indicates that more than 70 percent of the takeoffs were made toward the south. When the wind was from the north, aircraft from the field landed toward the north over plaintiffs’ property, and the study indicates that 29.8 percent of the landings were made over plaintiffs’ property.

16. The traffic pattern at Perrin Air Force Base has remained the same for the past 10 years. Under normal operating procedure, upon taking off to the north or south, the jet must first climb to an altitude of 500 feet above ground before making a turn to the west or the east, depending upon which runway is used. On an average day, the T-33 has a take-off roll of about 4,000 feet; the F-86, with afterburner, has a take-off roll of about 5,500 feet; and the F-102, using afterburner, has a take-off roll of about 3,000 feet before becoming airborne. All takeoffs to the south from either runway start at the extreme northern end of the runway used.

17. The ground elevation of the airfield is approximately 750 feet mean sea level. The ground elevation at various points on Tracts A and B within the approach zones to the two runways varies but generally exceeds 850 feet mean sea level. The ground elevation in the vicinity of plaintiffs’ improvements on Tract B is more than 100 feet higher than the elevation of the runways. On an average day at Perrin Air Force Base and under normal operating conditions when the temperature varies from 75 to 85 degrees and the wind is not more than 10 miles per hour, the T-33’s and the F-86’s were usually at an altitude of less than 500 feet above the terrain when passing over Tracts A and B after taking off to the south. Both of these aircraft have a longer take-off roll than the F-102 and each has a much slower rate of climb. In most of the takeoffs toward the south over Tract A, the T-33’s were approximately 200 to 300 feet above the terrain, while the F-86’s, with afterburners, were approximately 300 feet above the ground. Similarly, on takeoffs toward the south over Tract B, the T-33’s had a terrain clearance of about 300 feet, and the F-86’s, using afterburners, had a terrain clearance of approximately 350 feet over Tract B in most of the overflights. Because of pilot technique or weather conditions, there are occasional variations from the normal traffic pattern. The rate of climb of jet aircraft is higher in cool weather than in extremely hot weather. Therefore, on extremely hot days, aircraft taking off from the field to the south would be at lower altitudes over plaintiffs’ property than under average conditions.

As previously stated, the F-102 has a much more rapid rate of climb than either the T-33 or the F-86 and a considerably shorter take-off roll. On an average day and under normal operating conditions, the F-102 after taking off toward the south would be 800 feet above the ground when it passed over Tract A and from 1,000 to 1,200 feet above the terrain when it passed over Tract B. The distance between the point on the runway at which the F-102 is airborne on takeoffs and plaintiffs’ residence on Tract B is approximately 13,500 feet. Flight regulations at Perrin Air Force Base require the pilot to make a right turn after taking off from the west North-South runway upon reaching an altitude of 500 feet above ground elevation. Therefore, and except on infrequent occasions, the F-102 attains an altitude of more than 500 feet before it reaches Tract B, will make a 30-degree turn to the right, and will not pass over any part of Tract B. As stated above, however, the flight pattern is affected by weather conditions and pilot technique so that in a relatively small proportion of the takeoffs to the south, the F-102 flies over Tract B at altitudes below 500 feet.

18. The T-33, F-86, and F-102 are single-engine, jet-powered fighter aircraft. They are extremely noisy when taking off from the runways, because they operate at full military power. The F-86 (D and L models used at Perrin) and the F-102 were equipped with afterburners, which were used for additional thrust during takeoffs, and the noise, vibration, and disturbance created by these aircraft are considerably greater than that generated by the T-3B’s. The noise of the F-86 and F-102 on takeoffs is so loud and disturbing that the human ear can barely detect any difference in the intensity of the sound created by these aircraft when flying over Tracts A and B at low altitudes.

Plaintiffs offered evidence showing that when an electronic measuring device is used, the noise level of the F-102 is higher than that of the T-33, but the record contains no scientific data from which a finding can be made as to the comparative noise levels of the F-86 and the F-102.

19. The noise generated by the three aircraft operating at Perrin Air Force Base during the period pertinent to this action was substantially less when they flew over plaintiffs’ property on landing toward the north, because the aircraft always land under reduced power and without using afterburners. When the G.C.A. (radar ground control approach) landing procedure is used, all three types of aircraft pass over plaintiffs’ property on the average at approximately the same elevation above ground levels and at a height of about 375 feet above the terrain, When the planes are landing to the north under visual flying rules, the T-33 and the F-86 pass over Tract B on the average at a height of approximately 600 feet and over Tract A at a height of from 350 feet to 400- feet above the terrain. The F-102 has a steeper glide path for the final approach to the runway and, therefore, it lands over Tract A at an average height of approximately 500 feet and over Tract B at a height of 350 to 500 feet above ground level. For this reason, the F-102 is somewhat noisier on landing under visual flying rules than either the T-33 or F-86.

20. In the period from February 1953 to December 11, 1956, regular and frequent flights by jet aircraft operating from Perrin Air Force Base at altitudes below 500 feet over plaintiffs’ lands seriously interfered with the use and enjoyment of such lands. Such substantial and serious interference continued to the date of trial and will continue for an indefinite period of time.

21. As stated in finding 13, F-102 jet fighter aircraft were first assigned to Perrin Air Force Base in May 1960 and gradually replaced the F-86’s, which did not operate from the base after June 1962. Plaintiffs have not shown by a preponderance of the evidence that the interference with the use and enjoyment of their property was increased to any significant extent when the F-102 type of aircraft replaced the F-86’s at the base or that the value of such property was further diminished as a direct result of low overflights of the F-102 jets from Perrin Air Force Base. In the late spring of 1959, or approximately 1 year before any F-102’s arrived at the base, plaintiffs insulated the windows of their residence on Tract B for the purpose of diminishing the noise and disturbance created by jet aircraft flying over their house at low altitudes.

22. In view of the determination that defendant had taken a permanent easement for the flight of its aircraft in the airspace over plaintiffs’ lands prior to December 11, 1956, no finding has been made with respect to the amount of damages claimed by plaintiffs.

CONCLUSION OK LAW

Upon the foregoing findings of fact, which are made a part of the judgment herein, the court concludes as a matter of law that plaintiffs are not entitled to recover, and the petition is therefore dismissed. 
      
       In the late spring of 1959, or almost a year before any F-102’s arrived at the base, plaintiffs Insulated the windows of their residence on Tract B in an effort to decrease the noise and disturbance created by jet aircraft flying over their house at low altitudes.
     