Flap 25 and more

[cavaricooper]

As an inveterate BAW/CLX flyer (actually have been accused of heart palpitations when loading an airframe with anything other than RB-211s ) I habitually land with Flap 25, unless conditions specifically call for Flap 30.  I am noticing more and more YT videos using Flap 30, and am wondering if my methodology is now archaic?  The maintenance schedule of flap tracks vs. carbon discs I suppose.... coupled with the fact that most of these videos are now cargo ops.   Still nothing more beautiful than an RB-211 436 in a CPT departure turn out of 09R...

Also, I keep packs off for T/O at 300T+ and only use APU/PACK at particularly hot locales (i.e. VERY rarely).  The cabin climbs so slowly regardless, that I have been happy so far.... any need to re-evaluate?

Peter (et al RW operators) please comment as able...

Ta!

C

[Britjet]

Hi Carl.
F25 is fine.
Your rationale for packs is correct for BA ops.
Peter.

[John H Watson]

Peter (et al RW operators) please comment as able...

After the Qantas 744 ran off the end of the runway in Bangkok, their landings have always been 30.

Qantas takeoffs have been packless regardless of weight for the last few years.

[emerydc8]

I am noticing more and more YT videos using Flap 30, and am wondering if my methodology is now archaic?  The maintenance schedule of flap tracks vs. carbon discs I suppose.... coupled with the fact that most of these videos are now cargo ops.

You make a good point. With the kind of payloads we are hauling in cargo ops, we are often very close to our max structural landing weight (652,000 lbs). If the runway is less than 10,000', or if it's wet (even if more than 10,000'), most guys will choose to go with flaps 30 and autobrakes 3. On the 767, I have not landed the actual airplane with flaps 25 yet. I can see no advantage in doing so.

[Britjet]

All good stuff. If you are not restricted by weight, landing distance etc, then F25 would be optimum in my view.
It saves Flap load, which is never a good thing for the wings, but probably more importantly reduces engine noise on approach, and saves a little bit of fuel as well. Any Go-Around will have a touch more energy initially as well.
Boeing always refer to "Landing Flaps". The rest is up to you!
Peter

[cavaricooper]

Many thanks all... in this vein... I often use the BA "low drag approach" with Flap 20 gear up until 2000.... is this still being used as SOP?

Ta- C

[cavaricooper]

After the Qantas 744 ran off the end of the runway in Bangkok, their landings have always been 30.
Qantas takeoffs have been packless regardless of weight for the last few years.

John-

The 744 cabin climbs slowly enough where this is good everywhere except hot sticky locales... (Oz comes to mind immediately...   ) How do they handle cabin temps?

Ta- C

[Kieber]

...and just summarized for our hobby-pilots (sorry).

Comparing the two flap settings, the correlation of lift and drag results in certain advantages or disadvantages of either setting.

If flaps 25 is selected for landing flap setting, its lower drag requires less power, thus producing less noise and using less fuel. In addition, the performance, i. e. thrust available for acceleration is better than using flaps 30. Therefore, flaps 25 is recommended in conditions of possible windshear (e. g. gusty winds).

However, pitch attitude and approach speed are higher than with flaps 30, in order to produce the required lift. This leads to a disadvantage in forward visibility (cutoff angle) and increased landing distance.

So, whenever landing distance is a limiting factor (e. g. high weight and/or short runway, intersection turnoff, runway wet or contaminated, downhill slope, tailwind), flaps 30 is the preverable setting.   

In conditions of poor visibility the lower pitch attitude with flaps 30 increases the visible ground segment, thus increasing the chances to establish early visual refernce for landing (e. g. non precission approach, CAT II/III).

In some situations the higher drag of flaps 30 can be of advantage. The additional drag results in better power/speed stability. This is especially true on steep approaches (glide path >3°), in tailwind or with very low landing weight.

Whenever target speed for landing flaps 30 (VREF 30 + wind corrections) exceeds 167 kt IAS, flaps 25 and flaps 25 landing field length should be planned.

HTH
Walter 

[John H Watson]

The 744 cabin climbs slowly enough where this is good everywhere except hot sticky locales... (Oz comes to mind immediately...   ) How do they handle cabin temps?

I guess the packs are left on until just before the turn onto the runway. After takeoff, the packs are put on progressively during the climb.

[United744]

I always land flap 30:

* Slightly slower landing speed (helps saves the brakes)
* Pitch attitude is lower (better visibility)

While it is true the engines are spooled up more, burning more fuel and creating more noise, in the event of go-around the spool time to GA thrust is reduced by 1-2 seconds. Flap retract from 30 to 20 is IIRC 5 seconds, while gear retract is by far the slowest part at around 25 seconds. The flaps will be at 20 degrees before the gear is up, so no disadvantage vs. flap 25.

[Britjet]

I think Walter said it all, really...nice post..
And @ Carl - yes, the low drag approach down to 2000ft is fine in most circumstances..
Peter.

[cavaricooper]

Thanks All- Much appreciated!  There is no substitute for RW operational experience (no matter how much I read or watch).

Best- C

[John H Watson]

An interesting video on the QF incident...

https://www.youtube.com/watch?v=gR24_39ymkU&t