Hi guys,

 

I am enroute from EDDF - KIAH on Vatsim.   I was cleared to maintain runway heading on departure (rwy 18)  LNAV obviously was not armed, 179 was selected on the MCP and armed for capture on the FMA.  

 

After take off I engaged the A/P and the aircraft  made a hard right turn, I immediately disconnected the A/P, hand flew the aircraft whilst talking to departure & programming a direct-TO the next waypoint (not much fun single pilot!)  

 

 A/P was re-engaged and is now  behaving normally, the aircraft has behaved flawlessly for the past 82 hours of operation

 

So did I screw up at some point during preflight?  Departure on HDG select isn't exactly the most complicated procedure!   Have no idea what could have caused that behavior.

 

Cheers 

 

 

 

 

How did your lateral FMA mode (on the PFD) look before that take-off? Was TO/GA engaged (green) with HDG SEL armed (white) underneath it? 

How did the FMA change after taking-off and once the A/P was engaged?

Did the flight director command a right turn before engagement of the A/P? Did it command the turn after engaging it?

Did the selected runway heading on the MCP heading window change by itself after engaging the A/P or did the A/P turn to the right just like that, while the heading window was still set to the runway heading?

I am now pretty sure I know what I did wrong a very silly mistake.  FMA read TO/GA HOLD TO/GA VNAV

 

I armed HOLD whilst at the gate at a heading of roughly 360 (from memory)  I even noticed on the take of roll that the FD was commanding a right turn.  

 

Why I hit HOLD instead of HDG select is mystery. Been a long day and it's nearly 1am out here in Bahrain. Probably not the best time to start an 11 hour long haul to Houston!

 

Thanks

Great, that was easy!

 

Why I hit HOLD instead of HDG select is mystery.

 

That's what we have to try and figure out now! Let's see, how many hours of sleep have you had before boarding the plane? Do you feel like you're suffering from overall stress or cronical fatigue? Have you consumed any alcoholic beverages in the 8 hours prior to the flight?  

 

Standard procedure is a rum & coke during preflight! That probably explains it!  :biggrin:

Now that I've thought about it, I'm pretty sure you've flown the NGX for a while, am I mistaken?

 

You were probably used to clicking the HDG SEL button on the 737, which is exactly where the HOLD button on the 777 is placed. 

Nope, I studied the NGX but never flew it.  Been using the AS Advanced A320 on FS9 for a few years. Prior to that the PMDG 744 & MD11.

 

Regards

You can not arm a heading for take off! (unless rwy heading is programmed as a SID in the FMC in which case you can fly it with Lnav)

You have to set the heading and engage heading select once above 400ft.

 

If you leave TOGA engaged then that will maintain RWY TRACK after take off.

 

 

You can not arm a heading for take off!

How do you figure that? When clicking HDG SEL before lining up, aren't you arming the selected heading? Especially since the active mode on the FMA shows TO/GA, and the "armed" mode will show HDG SEL.

Well that would be something new for me.

As far as I know the only modes that can be armed are Lnav, Vnav, Loc, and Glide slope.

 

Armed would be if TOGA is green on the FMA and HDG is shown in white below it.

 

I will take a look at the PMDG777 in a few minutes and see what it does.

You can not arm a heading for take off! (unless rwy heading is programmed as a SID in the FMC in which case you can fly it with Lnav)

You have to set the heading and engage heading select once above 400ft.

 

If you leave TOGA engaged then that will maintain RWY TRACK after take off.

 

Hi Rob,

 

I am about to fly KIAH - KATL.  Just finished the preflight and have decided to test another take off in HDG SEL.  

 

FMA Reads    HDG SEL - TO/GA (Green) VNAV  (white)

 

I can also arm LNAV,  FMA reads the same as above except LNAV also displays (white)  I assume that just gives me HDG select until 400ft.

 

Anyway, you are correct that HDG SEL does not get armed, however It replaces TO/GA on the FMA

 

Will test this departure and check the FCOM enroute.

 

Cheers

Woops, you are correct, Rob... My mind must've been playing tricks on me ;-) Disregard my previous comment, please.

I get HDG SEL in green when I click on the heading select switch before take off.

 

Green means it is now engaged.

Not armed!

You have now exchanged TOGA for HDG SEL, which is not the proper way to do things (in real life. In FSX you can do as you please ofcourse).

 

Since most airlines are not allowed to make any turn before reaching 400ft, you want TOGA for roll mode during that first 400ft. (TOGA keeps runway track, to be more exact, ground track at lift off).

Passing 400ft AGL you select your heading and engage HDG SEL.

 

In the case of a runway heading it does not matter much.

Both TOGA and HDG SEL will give you approximately the same (depending on cross wind).

But imagine a take off clearance with a heading that is not rwy heading.

 

I just did a take off like that, with HDG SEL engaged (green=engaged) and even during take off roll WHILE ON THE GROUND the FD was deflected towards that heading.

Not something you want at all (in real life).

 

To be honest, I have never tried a T.O. with HDG SEL engaged in real life.

We dont try things we are not supposed to do :-)

So I dont know if HDG SEL can be engaged while on the ground in real life.

Woops, you are correct, Rob... My mind must've been playing tricks on me ;-) Disregard my previous comment, please.

No problem, I had to take a look at it myself :-)

What amazes me more is that HDG HOLD can be engaged on the ground! But you used to be able to engage the A/P on the ground so anything is possible on the 777

 

So to keep things simple Do not arm LNAV, Fly runway track in TO/GA, and engage HDG select after departure.

 

Cheers

I agree with 777simmer

 

I've never tried to "arm" HDG SEL on the ground, that's why I didn't know you can't actually arm it, only engage it.

 

On take-off you always want TOGA TOGA on your FMA until 400ft. Above that you can start changing A/P modes. On the heading selector you wanna have the runway heading or the first assigned heading.