Question on B767

[DeltaSix]

Guys,

Can I just throw a dumb question. Does the B767 if on Autoland mode, do a flare automatically ?..... is it does, at what altitude ?


Ta

D6

[esreverlluf]

Flare mode engages at 50' RA, autothrottle closes the thrust levers at different rates for different 767 models/engine types.

Hope that helps.

[Richard Kranium]

Yeah and it does a dam good job too, even in a crosswind...:yuk:

[DeltaSix]

You've answered my question, thanks for the reply


D6

[A37575]

Dunno about the 767 but the 737 will do a very smooth autoland using just one autopilot. The second autopilot is there for autoland regulatory requirements.

[Ralph the Bong]

Yep. Flares automatically. Start of flare is at 45' RA.

[DeltaSix]

Ralph and A37575

Is that the 737NG .... from what series of 737 do they have the auto flare on ?

Do you need to switch off the auto throttle on touch down ?
If not doesn't it look at the speed setting in the MCP and try to power up to maintain that airspeed ?

sorry, another dumb question.

Ta

[tinpis]

Are you planning a joyride Delta Six?:hmm:

[Speeds high]

Delta 6

the 733 has autoland available, however as the 737 has only a dual channel auto-pilot many states or companies do not allow there pilots to use the auto land feature.

The throttles maintain MCP speed until 50ft (?) then go into "retard" which closes them, the auto throttle automatically disconnects on touch down.

[DeltaSix]

g'day Tinpis, nah, just preparing by doing some reading on the 76 or 73 for a possible endorsement on either one for our company.

Thanks for the reply guys. I might throw in a question or 2 about the VNAV soon.


D6

[Waste Gate]

D6

I can answer your question on VNAV for you already - no, it doesn't work (not on the 76 anyway).:(

WG

[DeltaSix]

WG,

Now that you've mentioned it. I tried it on a sim and I got a bit confused. I don't have my notes with me but I thought it said that during the climb phase it uses the VNAV speed mode to lock in the target altitude and it would look at the lowest of the three settings ( MCP, the manually entered altitude in the LEGS page and the entered FMC CRZ ALT ). I dont know if I have done something wrong but I was quite sure that the alt in the LEGS page was lower but it took the MCP altitude instead ( which is higher ). I was also sure that the VNAV switch was on. Where did I go wrong ?

From your experience WG, which part of the VNAV does not work?

Also, in regards to IRS drift, how would you correct it if the IRS position is different from the FMC calculated position ?

I know that you cannot re-align the IRU in flight if it malfunctions, so can the Capt use the centre and right IRU or do you have to put the IRU in ATT mode to get the EADI back and re-enter the coordinates in the malfunctioned IRU to get the heading back in the EHSI if the IRU loses alignment ?

Thanks
D6

[Waste Gate]

Hi D6,

The least reliable part of VNAV is it's approach function. I've loaded the same approach to the same runway with the same speeds + altitudes on numerous occasions and watched in amazement as the aircraft has flown the approach differently each time.

Apart from that, VNAV actually works okay. It doesn't handle wind shifts - particularly on descent - very well, but I think that is common across most aircraft types. More accurate wind data would improve its performance in that regard.:ok:

Regarding your encounter with VNAV in the sim. . .

What you are saying is essentially correct, though I suspect you had entered the alt constraint as an "at or above" in the legs page. For example XXXXA, rather than just a hard altitude XXXX. In that case, the aircraft will continue climbing to the MCP altitude with VNAV SPD as the active pitch mode.

Had the alt constraint been entered as "XXXX" or "XXXXB" (at - or - below), then with the MCP altitude selected set to an altitude higher than the alt constraint, then the pitch mode will transition to VNAV PTH, and will remain so, until the waypoint or condition associated with the constraint is passed, after which the aircraft will continue climbing in VNAV SPD.:O

Regarding IRS failure . . .

The FMC position is a combination of IRS and navaid derived position (and GPS pos. where installed), so if the IRS position is drastically wrong, then the FMC position will also be wrong. There is no means of recalibrating the IRS position in flight.:{

The Capt's displays are fed by the left IRS. If this fails, then selecting "ALTN" selects the centre IRS as the source. No use of the "ATT" mode is required there. It is only selected when all 3 IRSs fail. Then, it provides only attitude and heading information, requiring entry of magnetic heading from the stby compass. All position information is lost.:confused:

WG