Confidential Human Factors
Incident Reporting Programme
The Charity
Aviation
Maritime
FC5339
Initial Report
The main 737 flightdeck jump-seat and centre console have been in the same position since the aircraft came to market over 50 years ago, yet the height of the average European/American person has increased around 6cm. The legroom provided is less than in the passenger cabin, and is further restricted by the centre console which goes all the way to the floor meaning you cannot put your feet under it. The seat is also poorly padded, and has a 90 degree angle between the seat and the seat back. The scale of the training operation at my airline means I will be sat on the seat on at least 6 sectors per month, as will safety pilots. Obviously changing the design of the seat would be a huge task, however there should be mitigations put in place to reduce the amount of time spent sat on it. For example rostering line checks on UK-Canaries sectors (4+hrs each way) should be avoided, and limited to flights of say 3hrs or less. The Company has no interest in introducing anything that make rostering less flexible, and takes the attitude that if the jump-seat is approved by regulators then there should be no restrictions on its use. I regularly leave the aircraft with two ‘dents’ in my knees where the top of the centre console has been pressing into my knees â if this was in any other workplace it would not be acceptable.
Airline Comment
CHIRP contacted the airline concerned but there was no response to our repeated requests for their perspective on extended use of B737 jump-seats.
Manufacturer Specification
With the help of our AAIB Advisory Board member, we were able to find some Boeing data from the original certification specs for the B737. Boeingâs sizing for the 737 observer seats was drafted to consider occupants in the range of heights from 5ft 2â (157.5 cm) to 6ft 3â (190.5 cm) in height. We were not able to locate similar ranges for occupant weight/mass, or for other more specific sizing criteria for individual body measurements. The seat is designed to fit within the physical space available in the flight deck, with the following primary considerations:
- Physical space for occupants in the previously listed range of heights.
- Normal 16g Forward and 14g Down crash loading certification.
- Head-strike protection area for occupants in the range of heights above.
Given that certification was some time ago it is unlikely that there are more details than this. Looking at the 2020 Anthropometric data for US adults this would include around 95% of men and around 75% of women. That data is for US adults so there is no exact read across to worldwide populations, but it gives a guideline.
CAA Comment
It is for the operator to assess the use of the seat, its suitability for long periods, and what mitigations they might want to put in place. The CAAâs role is to identify if they have raised it as an issue and review what, if any, mitigations they feel are appropriate.
CHIRP Comment
Our Advisory Board members had much sympathy for the reporter, with those who had operated as B737 training/supervisory pilots being particularly vocal about the discomfort of B737 jump-seats. As we all know, the B737 was designed as a short-haul aircraft probably well before cockpit ergonomics became a mainstream consideration but theyâre now being used for ever-longer sectors as longer-range variants are developed. Although itâs perhaps unlikely that significant design changes will be made to the seats, mitigations such as better cushions or limited occupancy periods might be achievable. The potential associated musculoskeletal risks of such poor ergonomics are obvious, and there may also be long-term risks to health that should be taken into account for those who are regularly tasked to operate from these uncomfortable and awkward jump-seats for long periods of time.
Itâs disappointing that we couldnât get a response from the airline as to how they might mitigate longer duration flights for jump-seat occupants in the B737. CHIRP thinks that either a limit on the number of such flights being rostered over a defined period or the use of ârest seatsâ in the main cabin to provide opportunities for breaks would be appropriate. There would undoubtedly be cost implications in providing alternative ârest seatsâ in the cabin for jump-seat long-term occupants to take breaks in, but this should not be a barrier to recognising that the use of such seats on long sectors should probably be mitigated by appropriate periods away from the jump-seat or limiting their use to shorter sectors.
Weâd be interested to hear if other B737 operators have introduced policies for extended flights using the jump-seat, contact us at mail@chirp.co.uk for the attention of Director Aviation if you have any thoughts or information.