On November 24, 1971, a man hijacked a Boeing 727 and parachuted away, never to be found.

According to Wikipedia, this prompted (together with 2 other hijackings) the installation of "Cooper vanes" devices that prevented the opening of the 727 ventral airstair in flight.

In the United States, following three hijackings in 1972, the Federal Aviation Administration ordered that Boeing 727 aircraft be fitted with Cooper vanes.

Wikipedia cites "Beyond Fear: Thinking Sensibly About Security in an Uncertain World," which I don't have access to. I can find the same claim here and here.

I couldn't find any Federal Aviation Regulations specifically mentioning "727." I also couldn't find any Airworthiness Directives specifically mentioning "727" relevant to the situation. There is this one. Furthermore, the policy change isn't mentioned here.

  1. Did the FAA order the installation of "Cooper vanes" on Boeing 727 aircraft?

  2. Was the "order" in 1972?

I am asking this question because of a recent April 2 answer on Aviation.SE:

Boeing did have a small regional jet called the Boeing 727. This plane was designed to operate at smaller airports, with independence from ground facilities as a selling feature. The best example is that the 727 had built-in stairs in the rear underbelly of the aircraft. This could be opened in flight until some hijacker known as DB Cooper jumped out to make his escape.

Apologies if the background research is poorly conducted and irrelevant. I am not familiar with the best way to research historic and current FAA "orders."

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    $\begingroup$ This question has been asked on Skeptics.SE and wasn't well received. $\endgroup$ Commented Apr 11, 2019 at 16:11
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    $\begingroup$ Don't think anybody (source of bottom quote) who characterizes the 727 as a "small regional jet" has much credibility, or much clue. $\endgroup$
    – Ralph J
    Commented Apr 11, 2019 at 17:29
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    $\begingroup$ FWIW, Beyond Fear (I have a copy) provides no citation for that claim. $\endgroup$
    – StephenS
    Commented Apr 11, 2019 at 19:37
  • $\begingroup$ @StephenS Thank you for your comment. This clears up a potential avenue of time-wasting. $\endgroup$ Commented Apr 12, 2019 at 1:20
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    $\begingroup$ @RalphJ The quote came from a question titled "Why didn't Boeing produce its own regional jet?" (cited in the question above). All answers (and all upvoted) included the Boeing 727 in the list of Boeing regional jets. If you disagree with this classification, you should post a separate (and better) answer. $\endgroup$ Commented Apr 12, 2019 at 1:22

1 Answer 1


The answer to both of your questions is "yes". The FAA ordered, in effect, the installation of "Cooper Vanes" and did do so in 1972.

The reason you could not find the answer may have been that the modifications were not called "Cooper Vanes" by the FAA and nor was the FAA targeting the 727 specifically. Instead they addressed ventral and tailcone exits on any aircraft.

CFR 14, Part 25 (Airworthiness Standards: Transport Category Airplanes), Subpart D (Design and Construction, Emergency Provisions) contains, since 31st of December 1972, the following text (emphasis mine):

Sec. 25.809

Emergency exit arrangement.


(j) When required by the operating rules for any large passenger-carrying turbojet powered airplane, each ventral exit and tailcone exit must be--

(1) Designed and constructed so that it cannot be opened during flight; and

(2) Marked with a placard readable from a distance of 30 inches and installed at a conspicuous location near the means of opening the exit, stating that the exit has been designed and constructed so that it cannot be opened during flight

This rule was announced in the Notice of Proposed Rulemaking. Notice No. 72-15, Issued on June 6th, 1972.

It clearly references the hijackings as the reason for this change.


In spite of concerted efforts made by the FAA and the air carriers, incidents continue to occur wherein the safety of the flight of aircraft engaged in passenger-carrying operations under Part 121 of the Federal Aviation Regulations has been jeopardized by persons intending to harm the crew or take command of the airplane. On a number of occasions in recent hijackings, the ventral exit of an airplane has been opened and a hijacker aboard has parachuted from the airplane through that exit. The agency recognizes that every possible step must be taken to deter persons from boarding aircraft for such a hijacking purpose. Accordingly, the FAA deems it appropriate to propose certain amendments to Parts 25 and 121.

Specifically, it is proposed to amend Sec 25.809 to provide that, when required by the operating rules, for any large passenger carrying turbojet powered air-plane an approved means must be provided so that:

(1) takeoff cannot be started if either the ventral exit or tail cone exit is not locked; and

(2) neither the ventral exit nor the tail cone exit can be opened in flight.

A similar amendment is proposed to be made to Sec 121.310, to become effective with respect to persons conducting operations under Part 121 six months following its adoption.

However, it is to be noted that to achieve compliance with the proposed regulation both the ventral exit and tail cone exit would have to continue to meet all of the requirements applicable to their approval as emergency exits. Specifically, to achieve compliance, the conditions that would have to be met to obtain approval of modification to the locking mechanisms of these two exits are as follows:

(1) The mechanism must be locked while the airplane is aloft;

(2) Takeoff of the airplane cannot be started if either ventral or tail cone is not locked; and

(3) The exit must be available for use in the event of an emergency.

Since Part 25 is for airworthiness certification of new aircraft, an additional change was proposed to Part 121 so that operator of existing aircraft were given 6 months to apply the new rules to already certified aircraft.

Somehow the change to Sec 121.310 cannot be found in the FAA Regulatory and Guidance Library (at least not dated 1972), even though the final rule of 30th November 1972 includes it.

A revision of 121.310 from 1997 includes the text.

Special thanks to the FAA for making the pre-internet era rulemaking archives easily accessible through the internet.

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    $\begingroup$ I have accepted this answer. Could I ask how you went about finding it (e.g. tips)? This would be really helpful in the future. $\endgroup$ Commented Apr 12, 2019 at 20:36
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    $\begingroup$ Hello Barry, welcome to Aviation.stackexchange.com. Finding the rules and notices of rulemaking was harder than I thought. Experience with aviation regulations helped a lot. I knew that in regulations, rarely a solution (e.g. Cooper vane or more technical term) is mandated, but instead the desired effect is mandated. I also knew that to address already existing type certified aircraft, the FAA would have to address both the certification rule (e.g. Part 25) and the operational rules (e.g. Part 121). I also suspected that the problem would be address generically, not only on the Boeing 727. $\endgroup$
    – DeltaLima
    Commented Apr 12, 2019 at 20:47
  • $\begingroup$ Thanks for the detailed reply! You mentioned 2 very interesting points. I suppose what you mean is experience helped you find the regulations? $\endgroup$ Commented Apr 12, 2019 at 20:51
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    $\begingroup$ Ah, thank you so much! I don't think I would've been able to do this, even after hours of searching. $\endgroup$ Commented Apr 12, 2019 at 20:59
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    $\begingroup$ You're welcome. As I said, experience with these kind of regulations / being an aviation nerd helped a lot :-) $\endgroup$
    – DeltaLima
    Commented Apr 12, 2019 at 21:31

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