Flight director set up on T/O

[matchthehatch]

Two scenarios

I understand where svcta is coming from and makes a valid point regarding roll control in a low speed, low altitude situation. Imagine the following two scenarios involving a G200 at MGTOW, departing from a high-altitude airport on a hot day (a worst case scenario):

Selecting ROLL (wings level)
In the event of a failure of the left engine, the pilot will have to apply full right rudder. This alone will not allow the pilot to maintain runway heading, and he will end up somewhere to the left absent a bank of up to 5 degrees to the right, i.e. following the wings level command. If you factor in a crosswind from the right, he will end up even further to the left due to drift.

Selecting HDG
In that same condition, the pilot should be able to maintain the runway heading, as long as the crew has set the heading bug to align with the runway. The command bars will direct the pilot to maintain the runway heading. While the drift will still occur, the pilot stands a better chance of remaining in the protected area. Now I suppose it is possible to drag a wing, but the pilot would have had to have made a huge mistake before rotation by not setting the heading bug correctly, or by rotating the airplane while heading off of the runway.

For both flight director modes, remember that in the high and hot condition, the airplane is going to spend a much greater distance while climbing to an altitude at which it is safe to retract flaps. That 400' altitude requires a lot of horizontal distance to reach, subjecting the crew to a greater risk of leaving the protected environment.

 

[svcta]

You seem to understand the point that I'm making (perhaps a little too well, hmmmmmm) but I'm still not convinced that in the "hot and high" scenario that you present that it isn't that much important to handle the airplane gingerly at that point. Read that as: Hot and heavy = behind the curve. You've never told anyone to blindly chase any one single parameter in this regime of flight. When you're heavy, slow and managing a failed engine, you fly gently.

I think that we can agree on that as being sound advice. So if you would agree to disregard a flight director that was commanding a 30 deg. bank to reestablish a proper heading then I'd agree to add a little extra roll against my FD command in order to maintain the same heading. This would keep you closer to the command bars and should maintain the same heading. All the while doing it with better FD guidance than with HDG mode and with assurance that the aircraft won't be shedding lift because of higher than necessary bank angles to myopicly chase a heading.

HDG mode at 400', until that point I'd rather do my best to keep the wings level and gently manage my heading. This goes way back to basic fundamentals of aircraft handling. I routinely fly airplanes on the ragged edge of too slowly (props with parachutes on) and it is AMAZING how much lift you loose when you start aggravating a slow wing with ham fisted aileron input. Sometimes its the difference between flying and falling. Not that we're that close in our listed scenarios, but......why take a chance when you have this knowledge?

Obviously, it's still open for discussion.....what say the rest of you?

 

[matchthehatch]

(Fingers in ears)...I can't hear you. What did you say?

Let's call it pilot technique.

 

[svcta]

the above slightly edited for reread....

Honestly I think it goes a little deeper than technique. Not MUCH deeper, but a hair.

Unless we've established that we (neither) aren't really honoring the FD to begin with. Maybe we should turn it off in this case......

 

[batsky2000]

In all my years as a check airman, I have never seen soo much bable on such a non event subject. To pass your type ride or p135 check you must maintain runway heading per pts standards, or follow a SID if you are cleared for one. If you are that worried about hitting the wing to keep the wings level, then you have more problems than that. A V1 cut should be a non-event. When you hear V1, stay on the runway till you are staright and rotate, at that point, you should be wings level, no need to turn, if you loose an engine and rotate right after V1, then yes it will be a wild ride. I see too many people rotate after they loose an engine at V1, and they are all over the place. Hitting HDG and setting runway heading in your HDG bug will keep you staright, it does not limit you for anything

 

[ksu_aviator]

With respect, I think that you've misunderstood the question. I completely trust the pitch mode of the FD. If I set it to 11 or 12 degrees I believe that that is where it should be for a good first whack at getting me to a pitch angle that will give me the correct airspeed for a climb during an engine failure. My original question is posted above in an earlier post regarding what the best lateral mode for the flight director during an engine failure after V1.

See above for my thoughts on Heading mode VS. Roll (or TO/TO, if installed). It's a matter of which is more important until the 400' mark: Wings level and aircraft control, or following the FD to maintain a specific heading (as would be directed by an FD in Heading mode).

My point is that you shouldn't trust the pitch mode, that is why the other argument is not relevant. Matchthehatch brought up a good point when he talked about high hot and heavy. The pitch that gives you the magic airspeed that you need to climb will vary from sea level to a mountain airport, from a cold day to a hot day, from a light weight to a heavy weight. One pitch will not compensate for all of the variables.

If you can calculate a pitch angle based on all the variables that will give you a good airspeed, then you have a valid reason to use the FD. If that is the case, then we can debate the merits of hdg v lvl v nav modes.

In my opinion, hdg is the most appropriate mode, for all the reasons stated above. If you are worried about the FD commanding too much roll too fast, consider using 1/2 bank. But, we then go back to trusting the FD for all circumstances v trusting the FD for specific situations.

So the question becomes, what is the most reliable method for all situations that may arise during takeoff. Since the FD is not programed to handle certain contingencies, I'm inclined to believe that hand flying/raw data is the best method for this aircraft with that equipment.

But, that is just my opinion and if someone has a good reason to use the FD, I'd be willing to listen to it.

 

[Coool Hand Luke]

In all my years as a check airman, I have never seen soo much bable on such a non event subject. To pass your type ride or p135 check you must maintain runway heading per pts standards, or follow a SID if you are cleared for one. If you are that worried about hitting the wing to keep the wings level, then you have more problems than that. A V1 cut should be a non-event. When you hear V1, stay on the runway till you are staright and rotate, at that point, you should be wings level, no need to turn, if you loose an engine and rotate right after V1, then yes it will be a wild ride. I see too many people rotate after they loose an engine at V1, and they are all over the place. Hitting HDG and setting runway heading in your HDG bug will keep you staright, it does not limit you for anything

Agreed.

SVCTA asked for some opinions on how to set up the FD on takeoff, almost all of which recommend HDG mode for lateral guidance, but that doesn't agree with his "roll mode" FD technique and he just keeps trying to justify his method regardless of what everyone else is saying. It reminds me of guys that get hired at a new company and proceed to tell everyone that what they have been doing all these years is completly wrong and that he did it such-and-such a way at his old job and now everyone should change and do things his way, which naturally is the only correct way.

SVCTA, If I were one of the pilots at your new job I'd tell you that you don't work at your old job anymore, and that this is the way we do things HERE. Then I'd tell you to go and update all the Jepps and leave the flying to me. You need to show some respect for your new peers and try to fit in and do things thier way.

 

[batsky2000]

My point is that you shouldn't trust the pitch mode, that is why the other argument is not relevant. Matchthehatch brought up a good point when he talked about high hot and heavy. The pitch that gives you the magic airspeed that you need to climb will vary from sea level to a mountain airport, from a cold day to a hot day, from a light weight to a heavy weight. One pitch will not compensate for all of the variables.

If you can calculate a pitch angle based on all the variables that will give you a good airspeed, then you have a valid reason to use the FD. If that is the case, then we can debate the merits of hdg v lvl v nav modes.

In my opinion, hdg is the most appropriate mode, for all the reasons stated above. If you are worried about the FD commanding too much roll too fast, consider using 1/2 bank. But, we then go back to trusting the FD for all circumstances v trusting the FD for specific situations.

So the question becomes, what is the most reliable method for all situations that may arise during takeoff. Since the FD is not programed to handle certain contingencies, I'm inclined to believe that hand flying/raw data is the best method for this aircraft with that equipment.

But, that is just my opinion and if someone has a good reason to use the FD, I'd be willing to listen to it.

O.K. I will bite. You are now trying to compare performance with a lateral navigation mode? the 2 have nothing to do with the other. Selecting a Lateral mode such as HDG or NAV does not affect if you will meet a climb gradient req. when an aircraft is built, the FMS is built with software that has performance based on that aircraft. It does not matter where the command bars are, because when you program the performance section of your FMS, you will get a TO N1 or EPR target based on Temp., if you loose an engine, you will still make the climb gradient as long as you hold V2, on an aircraft such as the challenger we have APR, which is Automatic Power Reserve which boosts the other engine 5% if you blow one, plus the box will compute your climb gradient to tell you what you can make. But your logic is flawed to compare performance with a lateral navigation mode

 

[ksu_aviator]

O.K. I will bite. You are now trying to compare performance with a lateral navigation mode? the 2 have nothing to do with the other. Selecting a Lateral mode such as HDG or NAV does not affect if you will meet a climb gradient req. when an aircraft is built, the FMS is built with software that has performance based on that aircraft. It does not matter where the command bars are, because when you program the performance section of your FMS, you will get a TO N1 or EPR target based on Temp., if you loose an engine, you will still make the climb gradient as long as you hold V2, on an aircraft such as the challenger we have APR, which is Automatic Power Reserve which boosts the other engine 5% if you blow one, plus the box will compute your climb gradient to tell you what you can make. But your logic is flawed to compare performance with a lateral navigation mode

No. You completely misunderstood.

My point is that if the pitch function of the command bars is not accurate, it doesn't matter what the roll function is capable of. You don't want to use a set of command bars that are only half right.

 

[svcta]

Agreed.

SVCTA asked for some opinions on how to set up the FD on takeoff, almost all of which recommend HDG mode for lateral guidance, but that doesn't agree with his "roll mode" FD technique and he just keeps trying to justify his method regardless of what everyone else is saying. It reminds me of guys that get hired at a new company and proceed to tell everyone that what they have been doing all these years is completly wrong and that he did it such-and-such a way at his old job and now everyone should change and do things his way, which naturally is the only correct way.

SVCTA, If I were one of the pilots at your new job I'd tell you that you don't work at your old job anymore, and that this is the way we do things HERE. Then I'd tell you to go and update all the Jepps and leave the flying to me. You need to show some respect for your new peers and try to fit in and do things thier way.

Actually, I asked why people set it up the way that they do.

I appreciate all of the input. I really welcome all of it, but you see the only reason I stick to my point is that virtually no one to this point has answered the real question, which was one of why people choose the mode that they do. I definitely understand that the bulk of us use the one setting over the other, however most of the people who answered didn't say much other than "just because". So, please forgive me if I tried to make my point. I've been trying to generate a little conversation on the matter, that's all. And the only reason it came up is because it was recently on the table at my department; people were trying to decide "how we do it here". I raised my hand and tried to make a point.

If and when I'm handed an FOM, I will follow it, I assure you. I know how to play ball and I believe in standardization. The situation is not one of being with new peers, it's one of developing new procedures. Go update the Jepps, eh? At least we all see how you handle a question.

Thanks to the rest of you. I'll call it technique and do whatever the manual tells me to do.

Case closed

 

[Coool Hand Luke]

I'll explain the obvious.

ROLL mode provieds no lateral guidance at all.

That is why almost everyone uses HDG mode.

You can do a complete 360 deg. turn in ROLL mode with a wings level attitude the whole time if you don't use enough rudder in an asymmetrical thurst situation such as the loss of an engine.

 

[svcta]

I'll explain the obvious.

ROLL mode provieds no lateral guidance at all.

That is why almost everyone uses HDG mode.

You can do a complete 360 deg. turn in ROLL mode with a wings level attitude the whole time if you don't use enough rudder in an asymmetrical thurst situation such as the loss of an engine.

Yes, I'm aware. Do you understand the question that I've been asking? It seems as if you don't. Not trying to start anything here, it just seems like you haven't been hearing what I've been asking (in real world speak), or the point that I've made about why flight directors with a TAKE OFF mode (TO/TO, or other) use a roll mode for wings level guidance until the beginning of 2nd segment (roughly). Why do you think that is?

 

[Shag McNasty]

Dude, you can take off in HDG mode, NAV mode or you can punch either one at 50ft AGL if you feel like it. Where does it say you can't touch the flight guidance panel until 400'?

 

[LRvsH25B]

Dude, you can take off in HDG mode, NAV mode or you can punch either one at 50ft AGL if you feel like it. Where does it say you can't touch the flight guidance panel until 400'?

Look in the SOPs of any professional flight department and you'll find exactly where it says you can't touch the guidance panel until 400ft. That is such a critical phase of flight, you should be flying the airplane and not concerned about the guidance panel at that point. Emergencies excluded. Most professional pilots won't stand for those types of sloppy habits/procedures.

 

[Gulfstream 200]

The PF shouldn't be punching anything until the AP is on....