The United States appeals the district court’s judgment for plaintiffs entered after trial without a jury in this negligence action brought under the Federal Tort Claims Act, 28 U.S.C. §§ 1346(b), 2671 et seq. The action arose from injuries suffered by plaintiff Jay L. Caplan when he was struck by a falling tree as he worked as a tree cutter in a government-owned forest. We affirm the district court’s judgment for plaintiffs.
In approximately 1975, the U.S. Forest Service decided to institute a mass tree-killing program in several areas of the Daniel Boone National Forest, a federally-owned forest in Kentucky. The goal of the program was to clear out low quality trees to enable reforestation with higher quality trees. The Forest Service instituted the program in 1975 by injecting herbicide into most trees in designated areas of the forest.
In 1982, the Forest Service solicited bids for the cutting down of trees that had survived the 1975 mass herbicide treatment. Plaintiff Jay Caplan was a successful bidder, and in December 1982 he began cutting down live trees in several areas of the forest. Forest Service personnel informed Caplan of the mass herbicide treatment, but not the date of the treatment. Caplan could distinguish dead trees still standing from live trees that he was to cut down: dead trees or “snags” looked like poles with few or no limbs.
On April 11,1983, just as Caplan finished cutting down a live tree in a tract in the forest known as the “Mill Branch area,” a 30-foot long dead tree fell and struck him. The falling tree fractured Caplan’s vertebrae, and as a result he is a paraplegic. The district court found, and the government does not contest, that the dead tree’s fall was caused by a failure of the tree’s support system and the ground shock resulting from the fall of the live tree that Caplan had just cut down. The court found that the instability of the dead tree, which had been injected with herbicide in 1975 as part of the government’s mass herbicide program, resulted from root system decay that had advanced to such an extent that the tree was barely anchored in the ground: “[I]t was as if a telephone pole was supported by being stuck into six (6) inches of sand.” The court further found that the steep slope on which the tree was located and the gravelly, moist soil in which the tree stood enhanced its instability.
Plaintiffs brought this negligence action in April 1985 under the Federal Tort Claims Act, seeking damages of approximately $3.5 million. In October 1987, the case was tried without a jury, and in a memorandum opinion dated November 1987, the district court held that the government was negligent in failing to warn Caplan of an unreasonably dangerous condition in the Mill Branch area created by a large number of unstable dead trees. The court held that this negligent failure to warn was a proximate cause of Caplan’s injuries, and in a separate decision on damages the district court awarded Caplan $2,155,865.52 and his wife $250,000 for loss of consortium. The district court denied defendant’s motion under Fed.R.Civ.P. 59 for a new trial or to alter or amend judgment, and this appeal followed.
I.
The government argues that whether or not it was negligent in failing to warn Caplan of a dangerous condition in the Mill Branch area, it is immune from liability for Caplan’s injuries under the “discretionary function exception” to the Federal Tort Claims Act. The district court rejected this argument in its memorandum and order denying the government’s motion for new trial.
Under the Federal Tort Claims Act, the government’s sovereign immunity is preserved for
[a]ny claim based upon ... the exercise or performance or the failure to exercise or perform a discretionary function or duty on the part of a federal agency or an employee of the Government, whether or not the discretion involved be abused.
28 U.S.C. § 2680(a). If a case falls within the discretionary function exception to the *1316Federal Tort Claims Act, this court is without subject matter jurisdiction. Feyers v. United States, 749 F.2d 1222, 1225 (6th Cir.1984), cert. denied, 471 U.S. 1125, 105 S.Ct. 2655, 86 L.Ed.2d 272 (1985).
Although the boundaries of the discretionary function exception are not altogether clear, the Supreme Court has emphasized that the purpose of the exception is to protect governmental conduct involving the exercise of policy judgment:
The basis for the discretionary function exception was Congress’ desire to “prevent judicial ‘second-guessing’ of legislative and administrative decisions grounded in social, economic, and political policy through the medium of an action in tort.” The exception, properly construed, therefore protects only governmental actions and decisions based on considerations of public policy. In sum, the discretionary function exception insulates the Government from liability if the action challenged in the case involves the permissible exercise of policy judgment.
Berkovitz v. United States, 486 U.S. 531, 108 S.Ct. 1954, 100 L.Ed.2d 531, 541 (1988) (quoting United States v. Varig Airlines, 467 U.S. 797, 814, 104 S.Ct. 2755, 2765, 81 L.Ed.2d 660 (1984)).
In the present case, the government’s failure to warn Caplan of a dangerous condition in the Mill Branch area was not conduct involving the exercise of policy judgment. Rather, the relevant policy decision in this case was the government’s decision to deforest parts of the Daniel Boone National Forest in preparation for reforestation. This case is therefore governed by a line of cases holding that once the government makes a policy decision protected by the discretionary function exception, it must proceed with due care in the implementation of that decision. For example, in Indian Towing Co. v. United States, 350 U.S. 61, 76 S.Ct. 122, 100 L.Ed. 48 (1955), the Supreme Court held the government liable for the negligent operation of a lighthouse:
The Coast Guard need not undertake the lighthouse service. But once it exercised its discretion to operate a light on Chandeleur Island and engendered reliance on the guidance afforded by the light, it was obligated to use due care to make certain that the light was kept in working order ... and to repair the light or give warning that it was not functioning.
350 U.S. at 69, 76 S.Ct. at 126-27.
Similarly, in Reminga v. United States, 631 F.2d 449 (6th Cir.1980), this court held that the discretionary function exception did not apply to the government’s negligent preparation of a navigational chart.
The import of our holding in Reminga is that once having exercised the discretion to issue navigational charts, the government is accountable for its negligence in failing to locate hazards accurately on the charts it publishes. Erroneously locating navigational hazards on its charts, like running a red light with a motor vehicle and causing an accident, involves no discretionary function or duty. Having undertaken, in its discretion, to issue charts locating navigational hazards at all, the FAA was liable for doing so carelessly.
Myslakowski v. United States, 806 F.2d 94, 98 (6th Cir.1986), cert. denied, 480 U.S. 948, 107 S.Ct. 1608, 94 L.Ed.2d 793 (1987); see also Butler v. United States, 726 F.2d 1057, 1063 (5th Cir.1984). Thus in this case, having exercised the discretion to deforest the Daniel Boone National Forest, the government is accountable for its negligence in the implementation of this decision.
The government’s reliance on Myslakow-ski as support for its argument that the discretionary function exception should apply in this case is misplaced. In Myslakow-ski, plaintiffs sued the government for failure to warn of the rollover propensity of jeeps sold by the government pursuant to an “as-is-where-is” policy promulgated by the Post Office Department. This court held that the failure to provide warnings was within the discretionary function exception because the failure to warn was required by the government’s “as-is-where-is” sales policy.
*1317[0]mitting to require that any warnings be given concerning the performance of jeep vehicles ... was an inherent part of the discretionary decision to sell the vehicles “as-is-where is.”
Myslakowski, 806 F.2d at 99. In the present case, however, the discretionary policy decision to deforest parts of the Daniel Boone National Forest did not require, either directly or implicitly, omission of warnings. Therefore, the failure to warn in this case, unlike that in Myslakowski, should not be protected as part and parcel of the discretionary policy decision.
We hold that the discretionary function exception to the Federal Tort Claims Act does not immunize the government from liability for Caplan’s injuries.
II.
The government challenges the district court’s holding that it was under a duty to warn Caplan of the dangerous condition in the Mill Branch area created by the large number of unstable dead trees. Under Kentucky law, it is well established that a landowner owes invitees
“a duty to use ordinary care to have his premises in a reasonably safe condition for use in a manner consistent with the purpose of invitation, or at least not to lead them into a dangerous trap or to expose them to an unreasonable risk, but to give them adequate and timely notice and warning of latent or concealed perils which are known to him but not to them.”
Standard Oil Co. v. Manis, 433 S.W.2d 856, 857 (Ky.1968) (citation omitted). The government argues that, under Kentucky’s “obvious natural hazard” exception to the landowner duty to warn, it had no duty to warn Caplan in this case.
Under the “obvious natural hazard” exception, Kentucky courts have absolved landowners of liability for failure to warn invitees of the dangers of icy walkways.
“In cases where there is no act on the part of the landlord creating a greater danger than was brought about by natural causes, the dangers that are created by the elements, such as forming of ice and the falling of snow, are universally known and unless the landlord has contracted to provide against these dangers, all persons on his property must assume the burden of protecting themselves therefrom.”
Standard Oil Co., 433 S.W.2d at 858 (citation omitted). The rationale underlying this exception to the landowner’s duty to warn of hazards on the land is that
natural outdoor hazards which are as obvious to an invitee as to the owner of the premises do not constitute an unreasonable risk to the former which the landlord has a duty to remove or warn against.
Corbin Motor Lodge v. Combs, 740 S.W.2d 944, 945 (Ky.1987).
We do not agree with the government's contention that the “obvious natural hazard” exception is applicable to this case. Unlike the risk created by ice on a walkway, the risk in this case — the hazard created by the large number of unstable dead trees — was not as obvious to the invitee as to the landowner. Although Caplan could observe many standing dead trees or “snags” in the Mill Branch area, he could not observe the extent of the root system decay in these trees. The district court found that this decay may advance to such an extent six or seven years after trees die that the trees may fall of their own weight or as the result of a very slight disturbance. Therefore, Caplan, who did not know that the government’s mass tree-killing process had been carried out some eight years earlier, and therefore could not have known how long the root systems of the dead trees had been decaying, was not cognizant of the dangerous condition created by the large number of unstable dead trees in the Mill Branch area. The government, on the other hand, was aware of the period that had elapsed since it had injected the trees with herbicide and it knew, or should have known, of the likely substantial root system decay and resultant instability of a large number of the trees. Because of its superior knowledge, the government was under a duty to warn Ca-*1318plan of this dangerous condition in the Mill Branch area.1
III.
The government also argues that the district court erred in holding that the government was negligent in not informing Caplan of the date on which trees in the Mill Branch area were treated with herbicide. We note initially that the government takes an unduly narrow view of the district court’s holding. In its negligence holding, the district court did emphasize the importance of knowledge of the date of the herbicide injections — because root system decay and tree instability increase with time passage after injection. However, the court’s negligence holding was not based solely on the mere failure to advise Caplan of the injection date; the court held that the government was negligent in failing to warn Caplan of the dangerous condition in the forest that had resulted from the substantial passage of time after the injections.
This court’s standard of review of a district court’s negligence determination is a narrow one.
“[A] finding of negligence or the absence thereof will not be set aside unless the District Court’s determination is ‘clearly erroneous,’ under [Fed.R.Civ.P.] 52.”
“If the district court’s account of the evidence is plausible in light of the record viewed in its entirety, the court of appeals may not reverse it even though convinced that had it been sitting as trier of trier of fact, it would have weighed the evidence differently.” However, when the “reviewing court on the entire evidence is left with the definite and firm conviction that a mistake has been committed,” the findings of the district court will be overturned.
Keir v. United States, 853 F.2d 398, 412 (6th Cir.1988) (citations omitted).
We hold that the district court’s holding that the government was negligent in failing to warn Caplan of the dangerous condition created by the substantial number of unstable dead trees in the Mill Branch area is not clearly erroneous. By merely informing Caplan that the herbicide injections had occurred, the government did not satisfy its duty to warn Caplan of the dangerous condition. Root system decay is a function of time; thus, knowledge that the injections had occurred was virtually meaningless without knowledge of when they had occurred and of the likely root system decay and tree instability attendant with the passage of time following the injections.
The district court’s judgment for plaintiffs is AFFIRMED.
. Because the government had superior knowledge of the dangerous condition, we also reject the government’s argument that Caplan’s status as an independent contractor absolved the government of a duty to warn. Under Kentucky law, "if the defect or danger is hidden and known to the owner, and neither known to the contractor, nor such as he ought to know, it is the duty of the owner to warn the contractor.” Simmons v. Clark Construction Co., 426 S.W.2d 930, 934 (Ky.1968).