Opinion for the Court filed by Circuit Judge MIKVA.
Dissenting opinion filed by Circuit Judge SENTELLE.
William Barwick sued Otis Elevator Company (“Otis”) for injuries resulting from the malfunction of an Otis elevator at the John F. Kennedy Center in Washington, D.C. A jury returned a verdict in favor of Mr. Barwick for damages of $4000. On appeal from the judgment entered on the jury’s verdict, Otis challenges the district court’s denial of its motion for directed verdict, and the court’s instruction to the jury on res ipsa loquitur. We affirm the judgment of the district court.
I. Background
William Barwick entered an elevator in the Kennedy Center accompanied by three friends. The elevator began to ascend. It stopped between the third and fourth floors, jerked as if it were going up, and stopped again. The elevator lights flickered on and off several times and went out. Although the elevator was equipped with an emergency telephone, Mr. Barwick and his friends were unable to open the door to the telephone at first. They tried to summon help by ringing the emergency bell, banging on the door, and yelling. Mr. Bar-wick finally succeeded in opening the telephone door and called for help. There were no Otis maintenance personnel on duty, so an emergency repairman was called. Some two hours after the initial stop, the elevator finally ascended, and the plaintiff and his companions were able to get out. The emergency repairman found the elevator to be “on safety.” Tellingly, he repaired it by changing the HI and H2 contacts. HI and H2 contacts are parts of the elevator control system that supply proper amounts of voltage and current for the motor to operate; an elevator goes on safety by coming to a stop whenever it overspeeds for any reason.
During this ordeal, Mr. Barwick experienced chest pains. He was treated initially at the Kennedy Center first-aid station and then transported to George Washington University Hospital. Mr. Barwick brought this action against Otis alleging negligence in failing to maintain the elevator in a reasonably fit and safe condition and failing to have emergency personnel available at reasonable times. A trial ensued in which Mr. Barwick relied on the res ipsa loquitur doctrine to establish Otis’ negligence. Otis moved for a directed verdict on the grounds that Mr. Barwick had not established a prima facie case of negligence and that the res ipsa loquitur doctrine was inappropriate. The court denied Otis’ motion for a directed verdict. The jury returned a verdict for Mr. Barwick, and the district court ordered judgment on the verdict.
II. Analysis
Federal jurisdiction in this case is based on the parties’ diverse citizenship. In a diversity case the district court and, on review, this court must follow local District of Columbia law. See Kuwait Airways Corp. v. American Security Bank, 890 F.2d 456, 460 (D.C.Cir.1989). We must therefore abide by the common law of the District of Columbia governing the doctrine of res ipsa loquitur. See, e.g., Bell v. Westinghouse Elec. Corp., 483 A.2d 324, 329 (D.C.1984).
A. Instruction Concerning Res Ipsa Loquitur
The principle of res ipsa loquitur “permits a jury to draw an inference of *394negligence based upon special circumstances where direct evidence of negligence is lacking.” Bell v. May Department Stores, 866 F.2d 452, 455 (D.C.Cir.1989). Before submitting the case to the jury, however, the court must determine whether the inference may be reasonably drawn by the jury, see Restatement (Second) of Torts § 328D(2) (1965), and the plaintiff must establish that: (1) the event was of a kind that ordinarily does not occur in the absence of someone’s negligence; (2) it was caused by an agency or instrumentality within the exclusive control of the defendant; and (3) it was not due to any voluntary action or contribution on the part of the plaintiff. Bell v. May, 866 F.2d at 455; Rassoulpour v. Washington Metro. Area Transit Authority (“WMATA ”), 826 F.2d 98, 100 (D.C.Cir.1987); Londono v. WMATA, 766 F.2d 569, 571 (D.C.Cir.1985).
As the parties do not dispute that the elevator was within Otis’ exclusive control and that Mr. Barwick did not voluntarily contribute to its malfunction, we focus our attention on the first factor: whether Mr. Barwick established that the event, defined as the elevator’s going on safety, ordinarily does not occur in the absence of someone’s negligence. Mr. Barwick must establish that, considering all other plausible explanations for the incident, the event was “most probably caused” by someone’s negligence. Bell v. May, 866 F.2d at 456. Barwick need not eliminate with complete certainty every other possible cause; he need only introduce evidence with sufficient probative force to support the inference that the plaintiff’s accident was probably the result of negligence. McCoy v. Quadrangle Development Corp., 470 A.2d 1256, 1261 (D.C.1983). The question is whether the trial judge properly determined that, in light of everyday experience or evidence in the record, a jury could conclude that the event was more probably than not the result of someone’s negligence. See Quin v. George Washington University, 407 A.2d 580, 583 (D.C.1979). If the answer is yes, we must affirm the decision of the district court. See Bell v. Westinghouse Elec. Corp., 483 A.2d at 329.
Mr. Barwick called Walter Hanner, a senior Otis Elevator supervisor, as an expert witness. Mr. Hanner’s testimony enumerated five reasons why an elevator could go on safety. As Otis concedes on appeal, however, undisputed evidence eliminated three of these explanations, leaving these two: (1) a momentary sag in electrical power, and (2) the burnout of HI and H2 contacts. Unlike the elevator malfunction in Bell v. May, which could have resulted from any of several equally plausible causes, the elevator malfunction in this case has been narrowed to two most likely causes. Compare Bell v. May, 866 F.2d at 457 (holding that res ipsa loquitur was inappropriate because plaintiffs had “made no effort either to rebut the non-negligent causes or to identify defendant’s alleged negligence as the most probable cause of the injury”).
At trial, Mr. Hanner testified that, “to a reasonable degree of scientific certainty,” the electrical power fluctuation was a “contributing factor” to the elevator’s going on safety, that Otis was not responsible for such power fluctuation, and that the burnout of the HI and H2 contacts can happen only when an elevator is descending (not when the elevator is ascending, as was the case in this incident). At his deposition, however, Mr. Hanner had testified, without ever distinguishing between ascent and descent, that the burnout of HI and H2 contacts was the “most likely suspect” of an elevator’s going on safety. When confronted with his earlier statement, the witness did not disavow it in any way.
Barwick has produced enough evidence from which a reasonable jury could conclude that the accident was more probably than not the result of someone’s negligence. Although Mr. Hanner testified at trial that a power fluctuation contributed to the accident, he conceded that on the same night (or, for that matter, at any other time over the course of several years), no other elevator in the Kennedy Center went on safety due to power problems. Thus, a reasonable jury could discount the power sag explanation relied upon by Otis, leaving the HI and H2 con*395tacts as the most plausible cause of the accident.
We must then evaluate whether a reasonable jury could have found that the failure of the HI and H2 contacts occurred, more probably than not, as a result of someone’s negligence. Mr. Barwick established that the emergency repairman changed the HI and H2 contacts that night and that the contacts normally need replacement every six to eight months. But Barwick could not, we stress, determine whether routine checks on the condition of the HI and H2 contacts had been properly performed, because Otis lacked complete records of its maintenance of the Kennedy Center elevators, and the particular HI and H2 contacts replaced by the emergency repairman were removed immediately after the accident. The res ipsa loquitur doctrine was intended to remedy precisely this sort of imbalance in information between plaintiff and defendants. Cf. Ybarra v. Spangard, 25 Cal.2d 486, 154 P.2d 687, 689 (1944) (“Without the aid of the doctrine a patient who received permanent injuries of a serious character ... would be entirely unable to recover unless the doctors and nurses in attendance voluntarily chose to disclose the identity of the negligent person and the facts establishing liability.”). Under these circumstances, a reasonable jury could conclude that the elevator malfunction was probably caused by the undiscovered deterioration of the HI and H2 contacts.
Otis asserts that the jury verdict contradicts Mr. Hanner’s trial testimony that the HI and H2 contacts could burn out only when the elevator is descending. A reasonable jury could have discounted Mr. Hanner’s assessment in light of his affiliation with Otis and his earlier deposition statement that the failure of the HI and H2 contacts was the “most likely suspect” of an elevator’s going on safety. Mr. Hanner’s deposition testimony was admissible at trial, not only for impeachment purposes but also as substantive evidence. See Fed.R.Evid. 801(d)(1)(A); Harley-Davidson Motor Co. v. Bank of New England, 897 F.2d 611, 615 (1st Cir.1990) (noting that where the defendant had impeached plaintiff’s expert by pointing to inconsistent statements in his depositions, such statements were also admissible as substantive evidence);. United States v. DiCaro, 772 F.2d 1314, 1321 (7th Cir.), cert. denied, 475 U.S. 1081, 106 S.Ct. 1458, 89 L.Ed.2d 716 (1986). In sum, the trial judge properly concluded that a reasonable jury could find that the elevator accident in this case was caused by someone’s negligence, that the res ipsa loquitur instruction was in order, and that, accordingly, the jury could permissibly infer that Otis was negligent.
Our colleague’s initial emphasis on the second factor in the res ipsa calculus (namely, the supposed lack of proof that the event was caused by an instrumentality within the defendant’s exclusive control) is baffling. Otis never argued that it did not have exclusive control over the elevator and all of its mechanical components. In Bell v. May, this court focused on the first factor of the res ipsa tripod, and (by reading it in tandem with the second factor) required that plaintiffs show that the defendant was somehow negligent. Nothing in Bell v. May justifies extracting the second factor, as our dissenting colleague has done, and giving it independent significance. The law of the District of Columbia in no way supports such a reading.
[Ujnder the law of the District of Columbia the cause of [plaintiff’s] injury may be identified generally as the escalator rather than the particular, identified protruding object____ [T]he circumstance of being injured while standing on a moving escalator provides evidence that the escalator was the cause of the injury.
Londono v. WMATA, 766 F.2d at 574-75. Here, Mr. Barwick’s injuries were caused by the elevator, an instrumentality within Otis’ exclusive control. The possibility that the elevator’s malfunction was caused by some other prior agent or instrumentality in an extended causal chain is a question properly analyzed under the first res ipsa factor. To do otherwise would confound the three factors (rendering the third factor relating to contributing causes redundant) and make res ipsa loquitur indis*396tinguishable from normal prima facie negligence.
B. Denial of the Motion for Directed Verdict
A trial judge must direct a civil verdict where there can be “but one reasonable conclusion as to the verdict.” Anderson v. Liberty Lobby, Inc., 477 U.S. 242, 250, 106 S.Ct. 2505, 2511, 91 L.Ed.2d 202 (1986). “If reasonable minds could differ as to the import of the evidence, however, a verdict should not be directed." Id. at 250-51, 106 S.Ct. at 2511-12. In reviewing the lower court’s denial of a motion for directed verdict, “[t]he court must consider all the evidence available in the light most favorable to the non-movant, resolving all conflicts in the evidence in favor of the prevailing party below.” Bell v. May, 866 F.2d at 455. Our ruling on the propriety of a res ipsa loquitur instruction is dispositive of this issue as well. Because there was enough evidence from which a jury, applying the res ipsa loquitur instruction, could have concluded that Otis was negligent, a directed verdict for the defendant would have been inappropriate. See Washington Sheraton Corp. v. Keeter, 239 A.2d 620, 622 (D.C.1968).
III. Conclusion
Mr. Barwick established that the elevator’s going on safety was an event that was more probably than not a result of someone’s negligence. Therefore, the district court did not err in denying Otis' motion for a directed verdict and, instead, allowing the case to go to the jury with a res ipsa loquitur instruction. For the foregoing reasons, the judgment is
Affirmed.