Flight director set up on T/O

[ksu_aviator]

Valid arguments exist against using a flight director during takeoff. These arguments are especially valid if the flight director does not give you accurate information.

With fd's that have a takeoff function, the computers do compensate for a wide range of flight conditions and are a very good back up. Of course, and I doubt I have to say this, nothing substitutes for a good scan.

With fd's that don't have a takeoff function, the fd can, in certain situations, give confusing/misleading information. I would be very cautious of using a fd to give you information when the validity of that information could be in doubt.

 

[svcta]

All good points so far, but it seems like the answers are more focused on the Pitch setting of the FD rather than the Lateral mode. My questions concern the philosophy of setting the Lateral mode of the FD when a "TO" mode is absent.

What I'm driving at is "what mode do you use and why?" with respect to the lateral mode of your FD on takeoff.

Thanks and keep it coming!

 

[ksu_aviator]

All good points so far, but it seems like the answers are more focused on the Pitch setting of the FD rather than the Lateral mode. My questions concern the philosophy of setting the Lateral mode of the FD when a "TO" mode is absent.

What I'm driving at is "what mode do you use and why?" with respect to the lateral mode of your FD on takeoff.

Thanks and keep it coming!

None. If you assume that pitch mode is not accurate, why confuse yourself with having a FD that is only 1/2 right?

I personally fly using visual reference (when possible)to maintain the runway center line to 50 feet and then assigned heading after that. The FD does not come on until 400 feet (or acceleration altitude).

 

[svcta]

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).

 

[batsky2000]

I have flown Collins,Honeywell,and Smiths(Boeing/Airbus). I currently fly a Challenger 604 and G-IV. The Challenger has a Proline 4, and the G-IV has a Honeywell SPZ8000. The Collins is the first system that I have ever trainied with that you hit the TOGA button, and take off in ROLL mode. I asked why we don't arm HDG or NAV mode, and the Flight Safety answer was that is how it is done, no other answer. I have since found out that there is no reason why you can't select a Lateral Navigation Mode. So every time I fly, I select HDG or NAV, and NAV mode works great if you have a RNAV Departure, it arms HDG then after you rotate goes into NAV mode. I have always selected some kind of Leteral mode on every other aircraft that I have flown. Evertime I fly the G-IV I hit TOGA then HDG or NAV, same thing on the B737...So try it, works fine and there is NO LIMITATION saying you can't do it!!!

 

[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