There have been, and still are, enough crew mistakes & incidents with the 737 pressurisation system to say that it is ergonomically substandard. The system is over 40 years old – almost half the lifetime of aviation - and was one of the first to be designed for a crew without a flight engineer. The world has moved on and the science of human factors has helped us identify & make many improvements in cockpit design, the 737 pressurisation panel should follow suit.
If I had any input I would suggest the following to Boeing in order of priority:
1. As TM said above, change all pressurisation items in the checklists to be challenge & response.
2. Change the cabin altitude warning horn to a verbal warning, say “CABIN ALTITUDE” or similar. The current horn is a hangover from when the only warning sounds came from the aural warning module. We now have a remote electronics unit which has voice capability, eg “PULL UP” etc.
3. Change the MAN caption to amber so it will illuminate on recall. That way no crew can accidentally get airborne in manual mode. If you are intentionally in manual mode I don’t see a problem with having an amber light. A lot of other things must be u/s to fly in manual.
4. Separate the diff pressure & cabin altitude gauges, they can be confusing in a non-normal situation (trust me, I have seen a few bizarre ones on airtests!), particularly when they are moving in different directions.
5. Enlarge the gap between +4000fpm & -4000fpm which is presently about 15deg on a small gauge. It is difficult to tell which it is when at max deflection. Yes I have experienced both!
6. Make the manual open/close toggle switch a selectable position switch, ie you set a valve position rather than more open or closed.
- Boeing has changed this panel before from CPCS to DCPCS, they can do it again.
- M/C logic has changed before (on the ctr tank pumps), they can do it again.
- The checklists have changed before (no comment!!!), they can do it again.
None of the above suggestions, or others better than these, are impossible to implement. Why the resistance?
Panel photos
here for those not on type.
S&L