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737 Go-Around question

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737 Go-Around question

Old 15th Aug 2018, 10:31
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737 Go-Around question

If you press one of the TO/GA buttons within the criteria for engagement of go-around mode during a singe-channel ILS approach when you are still above the missed approach altitude, as set in the altitude window on the MCP - what would happen? I have searched through FCOM and FCTM without finding any satisfactory answers. I know what I would do if I end up in a situation like that, but I'm interested in a technical perspective.

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Old 15th Aug 2018, 11:03
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Exactly the same as with the normal go-around, except that the AFDS will stay in TO/GA mode until you change the pitch mode yourself or reset the MCP altitude to something above your current altitude. In simple terms, the aircraft will climb until it reaches it's performance-limited altitude.
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Old 15th Aug 2018, 12:55
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Originally Posted by FlyingStone View Post
Exactly the same as with the normal go-around, except that the AFDS will stay in TO/GA mode until you change the pitch mode yourself or reset the MCP altitude to something above your current altitude. In simple terms, the aircraft will climb until it reaches it's performance-limited altitude.
Thanks! Are you talking from experience or is this documented somewhere? Or maybe itís considered obvious..
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Old 15th Aug 2018, 16:58
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It's documented, sort of, in System Description ch. 4. Read it as; in the abscense of ALT ACQ or pilot selected pitch mode, the F/D Go-Around mode isn't terminated.
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Old 15th Aug 2018, 19:33
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Why should one dial in a M/A altitude in the MCP if above?

Last edited by gearlever; 15th Aug 2018 at 20:31. Reason: should, not would
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Old 15th Aug 2018, 20:23
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Perhaps with a platform altitude of 3000 and a missed approach altitude of 2000 for example.
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Old 15th Aug 2018, 22:37
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Originally Posted by gearlever View Post
Why should one dial in a M/A altitude in the MCP if above?
Look at LEMG/AGP charts for runway 13: MISAP 2000' but platform 12nm at 4200'
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Old 15th Aug 2018, 22:53
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One way around this is to press TO/GA, followed by FLCH. If done without too much pause, the Approach mode will terminate, the thrust levers will advance slightly, then reduce to a low setting compatible with the remaining descent altitude and the aircraft will continue descent to the MAP alt.

Depending on the installed FMS/APFD, the lateral mode may need to be selected to LNAV or HDG SEL.
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Old 16th Aug 2018, 08:19
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One way around this is to press TO/GA, followed by FLCH. If done without too much pause, the Approach mode will terminate, the thrust levers will advance slightly, then reduce to a low setting compatible with the remaining descent altitude and the aircraft will continue descent to the MAP alt.
I haven’t heard that before but I guess it would work.
You can do it nicely by retuning the Nav receivers and then engaging V/s and whatever lateral mode you think is best at the time.
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Old 16th Aug 2018, 09:38
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Originally Posted by Skyjob View Post
Look at LEMG/AGP charts for runway 13: MISAP 2000' but platform 12nm at 4200'
I know.
Oor SOP was (retired) to set 2.000 ft, or whatever G/A altitude, when below.
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Old 16th Aug 2018, 14:44
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SOP in our company is to set the M/A altitude when when the GS is captured. I often fly in to Stockholm (ESSA) where the missed approach is 1500 ft and the platform altitudes at the highest 4000 ft. Thatís why this question have been a particular interest of mine. Thanks for all answers!
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Old 16th Aug 2018, 16:10
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This is why you brief on how you will perform the go around. Simple way of doing it.

1. Press CWS (this will take it out of APP mode)

2. LVL CHG

3. CMD A/B

This keeps the aircraft in an automatic mode and you wont need to rush when doing it.
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Old 16th Aug 2018, 21:06
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Hallelujah and praise Father Dick!
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Old 16th Aug 2018, 21:33
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Originally Posted by Father Dick Byrne View Post
Or you can simply fly the aircraft.
True, and I support the concept; but that's no reason not to be able to also do it by use of autopilot (with the weird sequence of commands in the edge case thought through ahead of time rather than during an actual goaround)
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Old 19th Aug 2018, 08:40
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If you want to do it simply. Why not just deselect the ILS frequency then re-select it. That will put you in raw modes. You can then select LNAV and V/S. Far smoother than LVL CHG which is a crude thing when you're near the ground. You've probably got some power on and don't want to drop onto the MA platform like a stone do you?
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Old 23rd Aug 2018, 07:38
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Originally Posted by RVF750 View Post
If you want to do it simply. Why not just deselect the ILS frequency then re-select it. That will put you in raw modes. You can then select LNAV and V/S. Far smoother than LVL CHG which is a crude thing when you're near the ground. You've probably got some power on and don't want to drop onto the MA platform like a stone do you?
For a descent I would agree with you. For a climb, I would use my method. I have used it both in the sim and on the line with no problems.
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Old 23rd Aug 2018, 09:11
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On 777 it will go into an unrestricted climb, 737 and 777 are pretty similar.

Easiest way is if your given a missed approach, before you press TOGA check the altitude selected. The is very rarely a rush to do a go around. If your above the missed approach altitude (on 777 anyway) so long as your above 1500ft if you deselect approach it will default to V/S and decent to and capture the missed approach altitude. When its level then select TOGA and follow the normal procedure.
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Old 23rd Aug 2018, 13:13
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Originally Posted by felixthecat View Post
On 777 it will go into an unrestricted climb, 737 and 777 are pretty similar.
Easiest way is if your given a missed approach, before you press TOGA check the altitude selected. The is very rarely a rush to do a go around. If your above the missed approach altitude (on 777 anyway) so long as your above 1500ft if you deselect approach it will default to V/S and decent to and capture the missed approach altitude. When its level then select TOGA and follow the normal procedure.
737 does not allow you to deselect APP, hence deselecting ILS is better option, forcing APP to be dropped.
BTW: only selected autopilot needs deselecting, eg NAV 2 with CMD B
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Old 23rd Aug 2018, 16:18
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Originally Posted by felixthecat View Post
On 777 it will go into an unrestricted climb, 737 and 777 are pretty similar.

Easiest way is if your given a missed approach, before you press TOGA check the altitude selected. The is very rarely a rush to do a go around. If your above the missed approach altitude (on 777 anyway) so long as your above 1500ft if you deselect approach it will default to V/S and decent to and capture the missed approach altitude. When its level then select TOGA and follow the normal procedure.

So you are saying you allow it to capture the missed approach altitude, then select TOGA? I'd say that's a bit dramatic.. Why not just wind a bit of speed on and clean up smoothly?
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Old 24th Aug 2018, 04:17
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It sequences the checks and systems but does nothing else.
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