These consolidated appeals are from money judgments which were awarded by *692the United States District Court for the Western District of Oklahoma, Grant v. United States, 326 F.Supp. 843, to the above named residents of Oklahoma City as a result of property damage from a series of high altitude flights carried out under the direction of the Federal Aviation Administration at supersonic speeds at high altitude. The tests were conducted pursuant to 49 U.S.C. § 1353 (b), which section authorizes the FAA to undertake or supervise development work and service testing in the interest of improving aircraft. These particular tests were for the purpose of assessing the effect of sonic booms on persons and building structures.
Prior to the commencement of the tests the FAA announced that it would pay for any damages caused by its sonic booms. In fact, the FAA set up a claims program through the Department of the Air Force under the Military Claims Act (10 U.S.C § 2733) for the purpose of processing claims flowing from sonic booms. Numerous of these claims were paid. Many others were determined to be invalid and were rejected.
A large number were filed in federal district court under the Federal Tort Claims Act, 28 U.S.C. § 1346(b). Involved in these was property damage, that is, cracking of plaster walls. The issue disputed in the district court and here as well was whether the damage was a proximate result of the sonic booms and, secondly, the correctness of the awards of damage. The district court resolved these issues favorably to the claimants against the government and this court sustained the findings. See United States v. Gravelle, 407 F.2d 964 (10th Cir. 1969).1
The cases which are before us on appeal were filed in court after the running of the two-year statute of limitations applicable to the Federal Tort Claims Act. Because of this fact the cases were considered under the Tucker Act, 28 U.S.C. § 1346(a) (2).2 The trial court reasoned that Gravelle, supra, had not held that recovery under the Tort Claims Act was exclusive, and proceeded to determine that the plaintiffs had effective remedies under the Tucker Act on one of two alternative theories: either that of a taking (in violation of the Constitution) or a remedy growing out of a contract, express or implied.3
*693In construing this court’s opinion in Gravelle as holding that relief was not limited to a remedy under the Tort Claims Act, the trial court pointed to an observation that the conduct of the government was willful. Liability under the Tort Claims Act arises only if the conduct of the agent of the government was negligent. Thus, according to the trial court’s view, the relief could not have been granted under the Tort Claims Act, and hence it had to have been granted under the Tucker Act. We disagree with this. Read in its entire context, the opinion of this court did not expressly or by implication hold that the Tucker Act was available to claimants in the situations of the plaintiffs-appellees here. The litigation arose out of the Claims Act, and relief was granted under that Act. The characterization as to the willfulness of the conduct was obviously not intended to characterize the tort as willful as opposed to negligent, for there was not the slightest indication in the case of intent to inflict injury. The willfulness was to conduct tests and these in turn created a risk of damage. It is, however, important to note in Gravelle the applicability of the Federal Tort Claims Act was not questioned by the government and was not considered by the court. The sole issues were sufficiency of evidence to establish proximate cause and whether the damage was minimal or substantial. Therefore, since Gra-velle does not even suggest that there can be relief under the Tucker Act, we are called on to determine for the first time (in this series of events) whether any facet of the Tucker Act justifies the granting of relief in the circumstances which are presented here.
The suits on behalf of Frey and Kirk were filed under both the Federal Tort Claims Act and the Tucker Act. The case on behalf of Cox was brought under the Tucker Act only. Similar suits were filed and were disposed of by Judge Bohanon who granted the government’s motion to dismiss based upon his prior decision in Bennett v. United States, 266 F.Supp. 627 (W.D.Okl.1965), which held that the kind of injury here presented was not a taking in the constitutional sense compensable under the Tucker Act.
The government here moved to dismiss on the basis that the plaintiffs were barred from recovery under the Federal Tort Claims Act by the two-year statute of limitations and, further, that there could be no recovery under the Tucker Act since there had been no taking of property.
The government concedes that in order to win public acceptance of the testing program, the FAA announced at the outset that it would pay for damages caused by sonic booms and it repeated this announcement of policy in conjunction with the defense of an injunction case filed in state court by citizens claiming that they had no adequate remedy under the Federal Tort Claims Act. The mentioned injunction was granted, and subsequently the case was removed to the federal district court, where the injunction was vacated and the action was dismissed for lack of jurisdiction. This latter decision was reversed by this court in Coxsey v. Hallaby, 334 F.2d 286 (10th Cir. 1964). On remand the district court determined that the test program was duly authorized by law, was reasonable and did not deprive the complainants of due process of law and that an adequate remedy at *694law was available precluding equitable relief. See Coxsey v. Hallaby, 231 F.Supp. 978 (W.D.Okl.1964).
The question presented then is whether a litigant claiming that his property was injured as a result of a series of high altitude tests at speeds in excess of the speed of sound producing sonic booms has a remedy under the Tucker Act either on the theory that there was a taking of his property by the government contrary to the Fifth Amendment of the Constitution of the United States or, in the alternative, whether the representation of government agents just prior to the commencement of the tests that it would pay damages resulting from injuries to property arising in connection with the mentioned activity constituted a contract, express or implied, giving rise to a claim under the Tucker Act.
I
The facts of this case do not lend themselves to a conclusion that there was a taking of property in violation of the Fifth Amendment to the Constitution of the United States. The guiding lights in this determination are the decisions of the Supreme Court in United States v. Causby, 328 U.S. 256, 66 S.Ct. 1062, 90 L.Ed. 1206 (1946), and Griggs v. Allegheny County, 369 U.S. 84, 82 S.Ct. 531, 7 L.Ed.2d 585 (1962). In the case at bar, giving full effect to the injuries incurred, it cannot be said that there was a taking, first, because of the isolated character of the injuries which were inflicted and, second, because of the absence of a permanent type of taking. An additional factor which militates against this being considered a taking is the extremely high levels of the flights, whereby the planes were passing through air space which is in law navigable.
In Causby the flights were at low levels and were so repeated and permanent as to constitute the imposition of a servitude on the land; thus, there was an effective taking of property interests of the land owner farmers whose chickens were lost as a result of fright. Furthermore, the occupants of the house were deprived of sleep and suffered ill health as a result of the activity. The Court in Causby recognized that the owner of land has limited rights to control the air space above his property. The Court also recognized that there need not be an actual trespass in order for there to be a taking. The fact that the easement might not have been permanent was not regarded by the Court as a factor which detracted from its being a taking.
The Supreme Court’s later decision in Griggs in essence applied the identical principle. Here the Court recognized the airport’s need for adequate takeoff and landing space and held that where noise from aircraft landing and taking off rendered a home located at the end of the runway unbearable for residential use, there was a taking of an air easement over the property. The county which was responsible for designing the airport was held liable to property owners.
It is clear from a careful examination of Causby and of Griggs that the present judgment cannot be affirmed upon the basis that there was a constitutional taking in accordance with the first facet of the Tucker Act.4
*695II
Next we consider whether there was an implied contract, and in this connection it is necessary that it be a contract implied in fact as opposed to one implied in law, commonly called a quasi-contract. 5 In order to have a contract implied in fact, there must have been a mutual agreement. Professor Williston has said:
This * * * class consists of obligations arising from mutual agreement and intent to promise but where the agreement and promise have not been expressed in words. Such transactions are true contracts and have some times been called contracts implied in fact. (1 Williston, Contracts, s. 3).
Professor Corbin has said that an implied contract includes those contracts actually intended and tacitly understood. 3 Corbin on Contracts § 563, 1960 Ed. Thus, then, there must be either circumstances or conduct from which it can be inferred that there was a meeting of the minds.6
This court has said that the elements of an express and implied contract are the same. The difference between them is one of proof. The express contract is proven by testimony showing the promise and the acceptance, whereas the implied contract is inferred from the acts of the parties and other circumstances showing an intent to contract. See Woodruff v. New State lee Co., 197 F.2d 36 (10th Cir. 1952) (opinion by Murrah, J.).
The government contends that there was no contract and could be no contract because the agents of the government were not authorized to enter into contracts. However, it is unnecessary — in view of our conclusion that no valid contract was entered into — to determine whether there was such authority. Offhand, it would appear in view of the breadth of the program that such authority did exist.7
Unquestionably the government stated publicly that it would pay for damage caused by the test program and had there been circumstances manifesting acceptances and a detriment or forbearance suffered in response to the statements of the government, it might be possible to conclude that there was an enforceable contract. The closest that the evidence comes to -something of this nature is the forbearance on the part of some of the people to proceed with injunctive actions. See Coxsey v. Hallaby, 334 F.2d 286 (10th Cir. 1964), wherein we determined that the issue of injunctive relief was genuine and not fictitious. Had these plaintiffs, then, refrained from instituting action as a result of the promise to pay there conceivably could be sufficient consideration to infer a valid contract. However, no facts appear from which such an inference may be drawn. In order to support a contract there must be an offer and an acceptance, together with a consideration. Here there is neither an acceptance nor is there shown to be consideration. None of the plaintiffs are shown to *696have relied on any statement or promise which the government made.8
So, therefore, the plaintiffs have not contended, and cannot contend, that they either had an understanding or were even lulled into a feeling of security whereby they did not file their claims within the two-year period required by law. The fact that the plaintiffs have now filed lawsuits does not constitute any acceptance of an offer on the part of the government. As we view it the government’s conduct was no open ended offer in any event. It was merely an expression that it intended to pay actual damage suffered, following which it set up machinery for the purpose of processing the claims. It did not undertake to entertain them and pay them indefinitely and long after the fact.
Apart, then, from the Tort Claims Act which has, as previously noted, a two-year limitation statute, and the Tucker Act which as has been shown does not embrace the damage in question, the government is immune from suit, and it is not possible to fashion a remedy which will permit the plaintiffs to prevail.
Accordingly, the claims are invalid and the judgments must be reversed with directions to vacate the judgments in favor of the plaintiffs-appellees. It is directed that the causes of action be dismissed.