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I was watching this video in which are described various systems on B737 but at around 6 minutes, it talks about speed brakes and necessity for pilots to maintain their hand on the lever to avoid forget to release them.

It seems perfectly sensible, but I'm asking why this is not a simple spring lever... if is very important that pilot don't forget lever in extended position, and for this reason is necessary that he's maintaining his hand on the lever, why don't make a simple lever that returns to default position after release?

This would sound even more secure... and in both cases pilot hand would be "busy".

Vikki
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Luca Detomi
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  • Are you asking about the 737 in particular, or about aircraft in general? Because IIRC all the aircraft I've flown (sailplanes) did have spring-loaded speed brakes/spoilers. – jamesqf Apr 30 '20 at 03:50
  • I discovered this feature on the 737 video linked but, sure, I meant about every aircraft. Now that you are saying that in sailplanes it's exactly like I proposed, it means that is not so "strange" as solution. So doubts increases about reasons behind a differen choice... – Luca Detomi Apr 30 '20 at 07:05
  • While I've never flown a 737, I'd guess it's all about complexity and workload. In a sailplane, you basically have a joystick and the spoiler handle, there's nothing else you need to use your hands for. In something like the 737, you might need hands for throttles, gear switches, radios, and maybe other stuff that the 737 pilots here could tell you about. But even going to something with an engine, like my Cherokee, the flap lever has several positions it locks in. Also, in a sailplane you are more affected by air currents &c, so you're using the spoiler as sort of an anti-throttle... – jamesqf Apr 30 '20 at 16:14

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Indeed spring-loaded or not, the pilot will keep a hand on it. But in the latter case, they can still use that hand, and return to the lever, without abrupt changes to the plane's pitch/configuration.

An example busy scenario is a rapid decompression descent.

enter image description here
Source: YouTube; annotated

If you continue watching the video past step 4 (deploying the speed brakes), there are other things the captain attends to with his right hand: pointing something out, making a call to the cabin, fine tuning the mode control panel, putting on the oxygen mask, inputs to the CDU, etc.

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    Oh right, very interesting video but... as you can notice, very often captain inctively put his hand on throttle and then come back to aerobrake lever, and then again on throttle but not to move them, it seems a very istinctive (understandable) movement. This is true especially in second part of video in which he spends many seconds out of this lever... It seems that possibility to forget it are not too low... Maybe co-pilot could help in this procedure, for example if it was a spring lever, co-pilot could mantain it while captain do other things... – Luca Detomi Feb 26 '20 at 09:14
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    @LucaDetomi: that complicates the workflow and solves no problem, btw if the thrust is increased the plane will sound and display a caution/reminder about the extended speed brakes –  Feb 26 '20 at 09:19
  • @LucaDetomi being able to "set & forget" the speed brake is very similar to setting trim. The pilot could maintain the plane's attitude by holding the yoke or side stick at the appropriate angle for the duration of the flight. However, the trim is there so he can get the plane to the desired angle, trim, and not worry about it until he needs to change. The speed brake is the same. It stays where it's set, allowing the pilot to do other things, until they need to be stowed. The habit of putting his hand back on the levers and the attention of the PNF will help prevent forgetting to stow them. – FreeMan Apr 30 '20 at 17:11