Capn.B
At last, I think I have identified the source of your angst. It is based on a misconception.
Red Herring. If in FLCH and HOLD, it looks to me like it will never automatically activate.
Simply not correct.
If you refer to the NTSB report 1.6.3.4 on pages 26 and 27, you will see a list of the circumstances in which the A/T will wake up out of HOLD. Hopefully this will allay your concern.
The basic premise of my comments was that if you follow the FCOM and SOP’s you will not get into any situation where the A/T will not wake up. What is difficult about that.
Approach 101.
If you follow FCOM and SOP’s, and If you have not yet captured the G/S you will have an altitude at or below your current level set.
Upon reaching that altitude the A/T WILL wake up and maintain ALT and SPD.
Upon transition to G/S, you may then select minima briefly then M/A alt.
This assumes you have the approach set up in your FMC and you are cleared to do so.
The aircraft will fly the profile both vertically and horizontally.
All that is required for you to do now is to configure and set speed as appropriate.
FLCH is no longer active once you capture the G/S or capture the platform ALT.
You are not in FLCH for the approach.
In the case of a visual approach, you can do all the same if you have and active ILS to help, or you can do it in VNAV or V/S if you have a published approach in the FMC.
Given that you are now in VMC you could also look out the window, and, heaven forbid, you could even fly manually in which case you should deal with the flight directors as described in the previous post.
If you are below the G/S when you select FLCH
AND do not set a lower ALT you will get to the situation that you deem to be dangerous,
and be in breach of FCOM and SOP.
I agree it is dangerous.
To my mind it is plain f..king stupid and beyond comprehension.
It is against FCOM and SOP’s.
Why would you do it?
As it is the only occasion that the A/T will leave you to determine your own fate, why is Boeing vilified for not putting in an idiot filter.
I repeat the challenge: If you know of any incident in this regard that has occurred after the crew have complied with FCOM and SOP’s, please tell us.
What's the TCAS, EGPWS, Takeoff Config Warning system for then? Or for that matter ABS in your car?
I am at a loss as to how any of this is relevant.
Are you suggesting that because you have these safety systems, you can forget about proper procedures, and just rely on the systems to keep you alive?
Good luck with that one.
Where do you want the donations sent in lieu of floral tribute.
An autothrottle that doesn't wake up even when you're almost 20kts below Vapp is stupidly designed. Period. Stop defending the indefensible.
It will only do what it is told to do. If you have set it up, and operate it as designed, follow FCOM and SOP, this question does not arise.
Even if you turn it OFF it will wake up at low speed, but if it sent into HOLD, by PF either directly or indirectly, it will do exactly that HOLD, until you tell it otherwise or it meets a selected altitude. (insert upon rereading; perhaps you misunderstand the meaning of HOLD. It relates to the autothrottle status, it does not indicate that it {auto thrust}will hold your speed. It is saying "your thrust sort it out yourself")
With regard to the FAA test pilot quote, you will note that just guidance material was made clearer. They didn’t see a need to change the hardware/software. And even test pilots screw it up on occasions.
As for using FLCH during an approach.
I don’t believe I have ever advocated that.
Frankly it was my preferred (non STAR) mode for descent prior to G/S capture (from above), particularly when operating in a speed controlled environment.
You seem to have a flea in your ear about the 777 and possibly Boeing, I hope this will relieve the itch.
As a post script:
I spent a considerable amount of time thrashing around Asia/South East Asia./EuropeI/Pacific and US, I often commented to colleagues that I was amazed that despite the plethora of 777’s in service throughout those areas, for new and small airlines, with many crews with limited experience, there were very few serious incidents, and at that stage no accidents. That in itself, to my mind, is testimony to the integrity of the design.
By the way you still haven’t answered my question about the 717 IAS HOLD.
Maui