set missed approach altitude in MCP

[aviateur22 0]

hello to alli'm trying to set the Missed approach altitude on VNAV approachin the FCTM , they say that we must set it 300ft below the missed appraoch altitude to avoid level-offbut 300feet below this altitude i will be already land // or i would already execute a missed approach // page 231for exemple i make a flt today at LIL/LFQQ , VOR appraoch RW08 , MDA is 353 feet i didnt have the time to set the missed approach altitude cause i've to landis there not an other solution to set this altitude?tks a lotcyril

[Fabo 213]

You are mixing your minimum descent altitude with your missed approach altitude. MDA, or Minimum Descent Altitude is the altitude you can not descend under, without visual contact with ground. You use the "Minimums" knob to set it. In some modes and procedures for non-precision approaches, MDA rounded up to nearest 100ft is set on MCP as not to let AP descend under it by itself, and also as a reminder by the crew. Note that this is NOT missed approach altitude.Missed approach altitude is the altitude you are supposed to climb to after a go-around. For example, your Missed Approach procedure might state that you are supposed to fly direct to a nearby VOR, and climb to 3000 ft. In this case, 3000 ft is the missed approach altitude. For VOR 08 in Lille, it is 2000ft (Climb on R-070 to D7.0 (VOR: to 1500'), then turnRIGHT (MAX 200 KT) to VOR climbing to 2000'.)

[rocketfs 2]

Fabo is correct.So if you fly a VNAV approach with DA(H) or MDA(H) of 1100', set the Missed Approach Altitude approximately the moment you descend through 1400'.Bert Van Bulck

[Spin737 102]

Fabo is correct.So if you fly a VNAV approach with DA(H) or MDA(H) of 1100', set the Missed Approach Altitude approximately the moment you descend through 1400'.Bert Van Bulck

I think you might want to work through that again. The missed approach altitude can be set when 300 ft below the missed approach altitude. This has nothing to do really with MDA and it doesn't have to happen the moment you pass through anything. The only time it has to be set is before you get to it on the missed approach.

[Daniel choen 23]

the missed app altitude should't be what you set after you disegage autopilot or after you capture the glide slope? i didn't know you can set a missed approach altitude on the fmc, where can i do that? thanks

[bakaman 28]

Flpas 15, gear down, landing lights on, arm speed brake, set MCP ( set speed as needed, alt and hdg ), Landing checks ! Missed approach altitude should be know by the crew since they have reviewed the missed approach procedure together way before landing .

[zubart 5]

Cyril.The point at which you reset the MAP altitude in the MCP altitude window has nothing to do with MDA or DA as stated above. For example, if the missed approach altitude for a given RNAV approach is 2000 feet MSL, then you would be able to reset the MAP altitude in the MCP altitude window when the airplanes MSL altitude passes below 1700 feet MSL (300 feet below the MAP altitude) during the descent. This applies to any approach.Take care,John Floyd

[Daniel choen 23]

ya we know the procedures, i think, but the mcp altitude should be set after localaizer eastablished, or after autopilot disengaged right?

[rocketfs 2]

I think you might want to work through that again. The missed approach altitude can be set when 300 ft below the missed approach altitude. This has nothing to do really with MDA and it doesn't have to happen the moment you pass through anything. The only time it has to be set is before you get to it on the missed approach.

Yup, I've been reading the 300-500 procedures.My bad!Bert Van Bulck

[bakaman 28]

Cyril. The point at which you reset the MAP altitude in the MCP altitude window has nothing to do with MDA or DA as stated above. For example, if the missed approach altitude for a given RNAV approach is 2000 feet MSL, then you would be able to reset the MAP altitude in the MCP altitude window when the airplanes MSL altitude goes below 1700 feet MSL. This applies to any approach. Take care, John Floyd

thats right! was just giving an example for an ils approach (actually thinking about a cat 1, since i do not fly much Rnav approaches) . there are no strict procedure for that according to what my instructors told me. once again that was just an example

[zubart 5]

ya we know the procedures, i think, but the mcp altitude should be set after localaizer eastablished, or after autopilot disengaged right?

The MAP Altitude can be reset:During a Precision approach, such an ILS approach anytime after GS capture. During a Non-precision approach such an a Localizer approach, after passing the FAF fix and established in a descent to the MDA or DA and 300 feet or more below the MAP altitude.The Autopilot has nothing to do with it.

[G550flyer 1,040]

The reason you are setting the missed app altitude is to get ahead and set your self up for success. This is like setting the next lower altitude during a non precision app after you reach your current step down altitude. On a precision/ILS app, you set it once you have glide slope capture. Now in the event you go missed, you are all ready set to capture the altitude. On some approaches, the missed app altitude is not that high above you making it easy to blast through it if your system isn't armed. Once you hit TO/GA, the system will capture the altitude as long as you have some type of vertical mode selected. So if you are going down to a MDA, I would set the altitude after the system goes into alt hold at the MDA. If you are VNAVing down to a DDA, you will have to set it on the go and treat the DDA like a DH. Think of the altitude select window as a stop sign. If you are descending in a vertical mode and you hit any altitude set it the window, the system will go into alt hold unless you are on a precision vertical mode. The OP gave us a MDA of 353. I would have 400 in the window, and would set the missed app altitude after I I'm in ALT hold at 400. Since you are in VNAV, you should technically be using a DDA of 403(MDA + 50ft). You would have to set the missed app alt on the go after reaching your mins of 403. If i was you, I would fly this as a IAN and set the missed app altitude after capturing the app mode. In the G550, the certification software delta of the avionics system allows us to fly an app in a IAN like mode. This allows us to set the missed app altitude after selecting the app button.

[Avroboeing 3]

I've been wondering the same thing. Thanks for bringing up the topic for discussion.So what happens when you're not given a MDA? Instead, all that you are given is a DA(h). Refer to the public chart below. I also have company charts, and they don't specify an MDA either. http://www.aip.net.nz/pdf/NZQN_45.3_45.4.pdfThe chart is for an RNAV(RNP) approach into Queenstown, New Zealand.The approach procedure I use is in the FCTM section 5.67 - Inst App - RNAV(RNP) SAAAR/AR.Ashley Frew.

[G550flyer 1,040]

This a special app for sure. My company isn't certified for RNP approaches but the aircraft we fly are. But in any case, treat it as a DH. Once you are on the app in app mode, i would set the missed app altitude. You have to be ready for the go-around as soon as you are outside of RNP tolerances. You have to make an immediate missed app if you receive a UNABLE RNP message and notify ATC.

[Avroboeing 3]

I suspected as much. I usually set the Missed Approach Altitude at the FAF for this approach, but was hoping someone would be able to provide specific guidance. Thanks Rick, appreciated.Ashley Frew.