737 Go-Around Query

[Analyser]

This is a query regarding an ILS appraoch and assume you are configured fully to manage the speed.Lets assume its a 737 NG.
When you are cleared for an ILS approach and you intercept the glide from above (Pitch FMA is now G/S and roll VOR/LOC) and the missed approach altitude is lower than your current altitude,If ATC were to ask you to go around and you press TOGA.what would the aircraft do.
For Eg. you are cleared to descend 3500ft,current altitude is 5000ft and you arm approach.She captures the glide.Missed approach altitude is 3000ft.On pressing TOGA the A/T would give you G/A thrust and the rest...?:rolleyes:

Please check out video link on next page

[FlyingStone]

Why would you even press TOGA if you are above missed approach altitude?

[underfire]

Depending on the manufacturers presets for arming (ac config and alt), it will advance thrust to GA and command the FD to climb on current heading.
TOGA will not engage until below 2000' RA, so with your scenario at 3000'...

Depending on the airport, you may not want to do this. This may not keep you in compliance with the missed approach procedure and routing. (ie continue descent to the MDA/DA...etc)

[Fullblast]

Undefire, TOGA will engage above 2000 ra if you have any flaps down; in the above case if atc ask you to go around you must follow the missed approach procedure, so continue descent to the missed approach level off altitude following the missed approach lateral path. In this scenario atc probaly would request to discontinue the approach giving a different clearance, anyway Analyser, if you push toga without setting the altitude above the current altitude, ac simply keeps climbing until you do something.

[JeroenC]

Flying stone: because your SOPs tell you to. I know, don't get met started.

GA is armed with GS capture OR below 2000 ft, so in this scenario it's armed.

The autothrottle will initially set thrust for 1000-2000 fpm climb, as normal with a climb GA. Can't remember the FD but IIRC same as with 'normal' GA: initially 15 degrees.

[Matey]

Get out of APP mode by disengaging autopilot and turning off flight directors, then reinstate suitable modes and automation levels (such as HDG SEL and V/S )whilst descending to the missed approach altitude. The next stage of the debate is what to do with the gear and flaps, and in what order.

[A37575]

Turn off all the automatics and hand fly the aircraft to where you want to go. Should be a seamless task if you are current on hand flying. Once everything sorted and aircraft in trim re-instate the required automatic functions at your leisure. A no-brainer.

[flyingchanges]

I would in no way consider this a go around, it would be merely abandoning your current situation. Pressing TOGA is going to turn a small problem into a big one.

[Wizofoz]

I THINK the 737s the same as the 777 in that above 1500' RA, APP mode can be deselected by pushing the APP button again.

This puts the AFDS into HDG HLD and V/S, which will then capture the MAP Alt in the MCP.

As a technique, you can THEN press TOGA- retract gear and clean up on schedule, engage HDG SEL or LNAV to follow the lateral path of the MAP.

[Rick777]

First off in this situation I can't imagine ATC telling you to "Go Around". They would cancel your approach clearance and give you another one which might be to fly the published procedure, but would probably be something else. At that point the advise in the response above this one would come into play.

[Analyser]

Thanks for the responses but will need have it checked out in the Sim.

I agree with Fullblast and JeroenC that the A/T will give go around power.I assume at some point in the climb she may command the pitch FD towards the missed approach altitude.
Switching off automatics does make it pretty standard as to what to do but the query was with the automatics on and more so on dual channel approach.

Wizofoz - once on the ILS the only way to exit the approach mode on the 737 will be TOGA,deselecting the ILS or A/P off and F/D's off.It may be different from the 777 coz once on approach with FMA's to G/S and VOR/LOC then only the above method will work.APP can only be deselected before G/S capture.

[GA_flps1]

Why complicate things so much when you have plenty of speed, terrain clearence and situational awareness? Why does a GA have to be so dramatic?


Gear up, flps 15,
Just retune the VHF nav1 and 2 to your MAP VOR to exit approach-mode,
tap some on the mcp (I would go with LNAV and a low VS rate or VOR/LOC + VS) Or even heading select + VS,
verify the FMA so that the aircraft is commanded to do what you want,
clean up the aircraft on schedule while descending and have the girls bring you a coffee as you hold :E

Piece of cake

I wouldn't press TOGA and disengage the AP and put the pilot monitoring into big work load with everything coming at the same time (rt, monitoring me, configuring a/c, callouts, tuning navaids, CDU entries, transition alts, altitude remaining callouts etc) as I'm having a 15 degree pitch up with a feather light plane when I should be descending instead within the congested TMA :8

[de facto]

Gear up, flps 15,


Wanna try that again?:p

[GA_flps1]

Wanna try that again?
Woops,

Well in my company we use the ultra-stable approach concept, sort of... :suspect::hmm:

[Matey]

De-tuning the ILS will indeed get you out of APP mode and into Control Wheel Steering. This is what we (Thomson) used to recommend, but our Regulator (UK CAA) was not happy with this for two reasons, and I agree. CWS is not a routine AFDS mode, and de-tuning the current navigational source leaves the aircraft descending without a navigational input. The upside is that the autopilot remains engaged albeit in a degraded and little used mode. Are we really that dependant on keeping automation engaged no matter what rather than going back to basics and then reinstating the automatics in a controlled and logical order into familiar modes?

[Pontius]

I think what Analyser was trying to ask was what would happen if you pressed the TOGA switches with a lower altitude than your present one in the MCP. As an example, ATC have cleared you to descend to 2000' and cleared you for the ILS. 2000' also happens to be the missed approach altitude. You arm APP, intercept the LOC and at, for instance, 3000' you intercept the GS. So there you are, 3000', APP engaged and 2000' in the MCP. ATC tells you to go-around and, for some reason, you decide to press TOGA. What happens next?

I believe it will climb on the present track and will have no altitude restriction to level it off i.e. you'll continue to climb at 2000 fpm until something is done about it. I don't think it will continue down the GS from 3000' to 2000' because the pitch mode obviously changes to GA and doesn't remain in GS. Having never tried this before I am entirely happy to be proved wrong.

My preference would be: A/P off and hold everything where it is, F/Ds off and then on again (now we'd have V/S and Hdg Hold), A/P on, LNAV for the missed approach track and leave it in V/S to capture the 2000' missed approach altitude.

[Artie Fufkin]

So there you are, 3000', APP engaged and 2000' in the MCP. ATC tells you to go-around and, for some reason, you decide to press TOGA. What happens next?

Nothing. TOGA arms at 2000 RA.

[Jwscud]

As the good book says (FCOM 2 4.20.17)

With the A/T Arm switch at ARM, the A/T go–around mode is armed:
• when descending below 2000 feet RA
• when above 2000 feet RA with flaps not up or G/S captured
• with or without the AFDS engaged.

[Pontius]

So, ignoring Artie's chaff we move swiftly on :)

[Artie Fufkin]

OK, my bad, the OP did say NG, not Classic.

[Breakthesilence]

Just try on the next flight, possibly in daylight, good weather and a low traffic condition. Then disengage the A/P and A/T and land manually or re-engage everything.

I don't think it is such a catastrophic challenge...

[contra-rudder]

We have standard company procedure for this situation.

- Set Missed app altitude
- Detune ILS from NAV1/2
- Disc. APP mode
- Descend in V/S and accelerate
- Clean UP in descend
- Level off and fly procedure

[mrjet]

Pontius got it right. In TOGA the AFDS does not consider what altitude is set on the mcp (it will of course attempt to capture a higher mcp altitude), the AFDS will always give a climb command in TOGA.

Last time I tried what the OP described in a sim I froze the sim at 15000' with the aircraft still climbing away from the mcp altitude.

[Analyser]

Thanks Pontius.You got my query spot on.She will continue to climb till something is done about it and this was checked out in the sim by a colleague.

Now please explain this...

https://www.youtube.com/watch?v=N1U_wWWhDNU

TOGA power at 30000ft on descent
with TMD reading CRZ and A/T commanding GA power.:hmm:

[AirRabbit]

Thanks for the responses but will need have it checked out in the Sim.

While I don’t argue with your intent, I would caution, before you make arrangements and jump into the simulator, you should check out whether or not the simulator has been appropriately programmed to function “just like the airplane” for any specific set of circumstances. Remember, simulators are little more than very fancy computers … and they will do only what they have been programmed to do, and this is true for EVERYTHING you see in the simulator. Don’t get me wrong, there are professionals who spend a great deal of time attempting to ensure that all of the interoperable systems are, in fact, interoperable and that all of the aerodynamics are, indeed, just like the airplane. But the simple fact is that unless the person who wrote the programming was supplied the correct “airplane answer” to systems interoperability and the airplane's aerodynamics, there’s a good chance that the simulator could give you a wrong answer without telling you that it’s wrong ... and, as a result, you might think that what you see in the simulator is accurate. This is why it is never a good idea to "grab a sim period" whenever you can, UNLESS there is a qualified and current simulator instructor available to make sure you don't take away the wrong idea ... and there are some circumstances where even the sim instructors are not fully aware of that simulator's limitations. Welcome to the world of simulation.

[flyboyike]

I can grab a cup of coffee in the breakroom at the sim building without an instructor being present, right, AirRabbit? Or will that be the wrong answer?

[BARKINGMAD]

Is this not a "discontinued approach"?

No need for TO/GA mode on anything, else the autos get confused as do the pilots.

Click-click and fly the aircraft to the required path and track with required energy.

F/Ds are redundant and potentially erroneous and maybe deselecting them til your oppo sorts out the APFDS could be a better MOI, and then you can go back to chasing the magenta spider again?

Just a thought from an old codger who likes K I S S!

[RAT 5]

Just a thought from an old codger who likes K I S S!

Every new cadet training file should have this front & centre on its cover. Boldly.

Got the T-shirt, but before we are all gone what about a KISS lapel badge or emblazoned tie. I did once write the letters on my epaulet gold bars, but it was frowned upon. There was a sense of humour failure. I was only trying to spread the gospel. I then took to wearing lucky socks and red underpants. It seemed to work considering my survival success.

[Aluminium shuffler]

I can think of a few places with GA alts of 1,500 feet or so AGL, so this is a real issue at those places. I have had a very new FO do his first GA at one of them because of a screwed up ATC instruction, so it was a real surprise (with such clear wx and runway) and he pressed TOGA. I had to pull the thrust back pretty sharply to prevent a flap speed excedence as he recognised the need to continue descending and kept the attitude steady, but forgot the thrust increase was so large for the attitude...

For clarity's sake, pressing APP again after it engages will not disengage the mode - it is one of a few modes that locks in, and this is indicated by the button's lights extinguishing on engagement; the light is only on when armed, and the mode can be deselected in that condition.

[axl76fg]

The A/P will disconnect and A/T add thrust to reduced G/A, F/D pitch 15deg nose up