On airliners, passenger seatbelts are simple lap belts. However, flight crews seem to have at least shoulder straps, and often five-point harnesses. Why do flight crew have more restraints?
8$\begingroup$ Is your question about why do pilots have 5 point harnesses, or why don't passengers? $\endgroup$– CGCampbellApr 3, 2015 at 12:10
- pilots need to be able to do work during turbulence.
- passengers don't really like to be fully restrained.
3$\begingroup$ I believe the primary reason for a shoulder harness is in case the pilot passes out and falls on the yoke $\endgroup$– BenApr 3, 2015 at 9:20
10$\begingroup$ @Ben I don't believe that is true. Like a race/performance car driver, a pilot cannot perform his duties while displaced from his seat. Any reaction great enough to pull his feet off of the pedals, or hand from the control device (be it yoke, or fbw joystick) means the plane continues to fly out of control. Bad. Bad bad bad. $\endgroup$ Apr 3, 2015 at 11:10
13$\begingroup$ @ben No, it cannot. Find your nearest car enthusiast and ask to take a ride. Get him to take you for a ride and go around a sweeping left turn. While in the turn, reach for the gear shift while your trunk/torso is pinned to the door. Now consider that a plane deals with three dimensions of turbulence often. Any time a pilot cannot safely reach whatever he is attempting to is a very bad thing. $\endgroup$ Apr 3, 2015 at 11:43
5$\begingroup$ I'd really like to see some of these comments worked into the answer. $\endgroup$– KRyanApr 3, 2015 at 17:57
3$\begingroup$ Even if the pilot could hold himself adequately in place and reach the controls do you want him fighting the turbulence or flying the plane? $\endgroup$ Apr 4, 2015 at 21:27
ICAO Annex 6, Part 1 states:
6.2.2 An aeroplane shall be equipped with:
c) 3) a safety harness for each flight crew seat. The safety harness shall incorporate a device which will automatically restrain the occupant's torso in the event of rapid deceleration
It also confirm's Ben's comment that they are also meant to restrain an incapacitated pilot:
Recommendation.– The safety harness for each pilot seat should incorporate a device to prevent a suddenly incapacitated pilot from interfering with the flight controls.
3$\begingroup$ if there is something downvote-worthy in my answer, i'd appreciate your input. $\endgroup$– ErichApr 4, 2015 at 6:19
1$\begingroup$ While shoulder harnesses might prevent the body of a slumped-over pilot from touching the yoke, it doesn't do too much if their hand is on a sidestick and pushes it forward, does it? $\endgroup$ Apr 4, 2015 at 17:00
2$\begingroup$ I do not think the recommendation with respect to restraining an incapacitated pilot indicates that is the primary purpose. In fact, this is a recommendation, while restraint under deceleration is required. Both concerns look to me to be targeted to inertia-style belts, as ordinary shoulder belts meet these requirements automatically, without 'devices' - are inertia belts used, or even allowed? (BTW: I did not down-vote.) $\endgroup$– sdenhamApr 4, 2015 at 17:20
2$\begingroup$ @robokaren with sidesticks, input can be overridden (see aviation.stackexchange.com/q/3455/6919). much harder to override actual movement on the opposite yoke. $\endgroup$– ErichApr 4, 2015 at 23:00
I recall early in my glider training when I was about 17 before Id gone solo. My instructor used to keep his shoulder straps loose so I started doing the same.
On my 1st actual cable snap on the winch tow I whacked the stick forward and the glider went into -ve g. It was an open-cockpit glider with no canopy and I was half hanging out and only just managed to reach and get fingertips of one hand onto the joystick to pull myself back into the plane. I stabilised the glider, pulled my straps tight, but then found out my instructor behind me was not responding. I landed safely and then found out he was unconscious. He had bashed his head on the wing above him and passed out.
I always had my straps fastened properly after that incident.
2$\begingroup$ Great anecdote, and I'm glad you both made it out alive! Unfortunately, not really an answer. $\endgroup$– FreeManOct 8, 2015 at 16:26
There have been some "unusual attitude" instances where the crew have recovered the aircraft but would have possibly been thrown from their seats or unable to reach the controls through excessive G if not fully restrained.
1$\begingroup$ China Airlines 006 is actually a bad example for this, from the final report: "not all of those interviewed could recall the events of the upset, the descent, and the recovery. Most of those who could recall said that they felt an initial period of moderate negative G forces lasting several seconds followed immediately by a period of stronger positive G forces lasting several seconds. The positive G forces decreased momentarily and was followed by a period of even stronger positive G forces lasting several minutes." $\endgroup$– FedericoApr 3, 2015 at 11:23
In airliners, shoulder harnesses are not installed for passengers because:
- it is not not mandated by law
- it is too much for average passengers to deal with
- it requires money to install
- it is superfluous in a crash when compared to the same safety from a lap belt
Flight crew is required to use the shoulder harness (when installed) as it is the law (14 CFR 91.105):
(a) During takeoff and landing, and while en route, each required flight crewmember shall—
(1) Be at the crewmember station unless the absence is necessary to perform duties in connection with the operation of the aircraft or in connection with physiological needs; and
(2) Keep the safety belt fastened while at the crewmember station.
(b) Each required flight crewmember of a U.S.-registered civil aircraft shall, during takeoff and landing, keep his or her shoulder harness fastened while at his or her assigned duty station. This paragraph does not apply if—
(1) The seat at the crewmember's station is not equipped with a shoulder harness; or
(2) The crewmember would be unable to perform required duties with the shoulder harness fastened.
5$\begingroup$ This only kind of deflects the question, though, doesn't it? The question just becomes "Why does the law mandate shoulder harnesses for pilots?" / "Why doesn't the law mandate shoulder harnesses for passengers?" which remains unanswered. $\endgroup$– KRyanApr 3, 2015 at 17:56
4$\begingroup$ I'd like to see a reference for "harness...is superfluous in a crash when compared to the same safety from a lap belt", in cars a full harness is superior to a single shoulder belt, and a single shoulder belt is superior to no shoulder belt (even with airbags). So I'd be really surprised if a shoulder harness provides no benefit in a plane crash. (though I can believe that since plane crashes are so rare, the expense and inconvenience is not worth it) $\endgroup$– JohnnyApr 4, 2015 at 0:46
$\begingroup$ @Johnny: IIRC, a lap+shoulder belt is superior to a single shoulder belt, but a single shoulder belt is worse than no belt. $\endgroup$– VikkiApr 3 at 0:20
If the plane is in turbulence, and the passenger is jostled about, injured, or even knocked unconscious, well, sucks for him, but he will recover.
The more extreme the situation, the more important it is that the pilot be conscious, uninjured, and stable.
For passengers, while flying I feel fully restrained around the hips by a lap belt fully tightened- it would be more comfortable to have the belt load spread out. A full car seat belt compared to a lap belt allows you full motion. Its more likely the cost and difficult of having more anchor points on all seats especially when they spread them across the plane- a place to join the belt to the seat at higher point. They might also have to design the seat to handle its load being more spread out. Let alone having to work out if having such "improved" belts actually helps survivability with the greater risk of being unable to unclip.
$\begingroup$ In car the shoulder strap is attached to the frame beside (or behind in the rear) the seat, so it can take very high loads. But in an airplane no similar attachment point is available in the passenger cabin (nor in a bus; some buses have belts for passengers, but they are also only lap belts). $\endgroup$ Apr 3, 2015 at 16:35
1$\begingroup$ @JanHudec Longer-distance buses in the UK are obliged to provide seatbelts by law. As I recall, the ones I take to the airport have full car-style seatbelts, not just lap belts. $\endgroup$ Apr 3, 2015 at 16:53
$\begingroup$ @DavidRicherby: Hm, I've only ever seen the lap ones here. $\endgroup$ Apr 3, 2015 at 16:56
The main function of a shoulder harness or five-point restraint (as opposed to a simple lap belt) is to provide upper-body restraint and keep the occupant's head and upper torso from flailing about during rapid decelerations.
If an airliner's about to crash, the passengers can be told to assume a brace position, which likewise keeps the upper body from flailing about, making a simple lap belt sufficient for safely restraining the passenger. The pilots, who have to (try to) fly the plane (or at least make sure it crashes as safely as possible), can't brace themselves, as this would prevent them from (e.g.) manipulating the flight controls; additionally, the area immediately in front of the pilots contains lots of potentially-injurious things, like the control yokes and various switches, buttons, dials, and levers, that the pilots' heads and upper torsos would smash into in the absence of upper-body restraint.
As a result of the more-injurious environment in front of the pilots and their inability to assume a brace position to protect their upper bodies in a crash, the pilots have restraint systems that provide upper-body restraint, such as shoulder harnesses or five-point restraints.