From photographs I see that there are both Flaps Forty and a Flaps Fifty detents on the Boeing 707 airlines I have seen. My question is whether Flaps Forty was ever used for landing on the 707. ???

A B737-200 pilot told me that there were two landing flap settings for that aircraft and that one provided for better handling in gusty or crosswind conditions.

Another pilot told me that he thought that some airlines used a lower flap setting when sufficient in order to reduce the noise footprint of the aircraft during landing.

Are there any Boeing 707 pilots out there who can answer my question?. I realize that various iterations of the 707 type airframe are used by military pilots so perhaps they know the answer. I am not sure noise abatement is a consideration for military aircraft though.

Thanks loads for any information and opinions!

convair880mfan wrote:

From photographs I see that there are both Flaps Forty and a Flaps Fifty detents on the Boeing 707 airlines I have seen. My question is whether Flaps Forty was ever used for landing on the 707.

A B737-200 pilot told me that there were two landing flap settings for that aircraft and that one provided for better handling in gusty or crosswind conditions.

Another pilot told me that he thought that some airlines used a lower flap setting when sufficient in order to reduce the noise footprint of the aircraft during landing.

Are there any Boeing 707 pilots out there who can answer my question?. I realize that various iterations of the 707 type airframe are used by military pilots so perhaps they know the answer. I am not sure noise abatement is a consideration for military aircraft though.

and from a previous thread several weeks ago, you asked,

Do any Boeing 707 pilots know if it was usual to use a flaps 40 setting for landing or whether flaps 50 was the preferred setting. I would imagine, although I could be wrong, that flaps 50 in the various models of the Boeing 707 created more noise and higher fuel burn.

I know for talking to pilots of other types of jetliners that the final landing flap setting could depend on things such as wind and other factors. Not sure if this would be true of the Boeing 707 jetliner.

Second, but related question for 707 pilots: Could one go from flaps 25 to flaps 50 without stopping first at flaps 40 or did one need to allow the aircraft to slow at flaps 40 before it was safe to lower the flaps to the 50 setting?

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convair880mfan, I have combined your two threads. I'll do my best to try to answer some of your questions.

Also, I'm not familiar with the Boeing 707. KC-135, yes. Will that do?

The KC-135 flap increments are 20, 30, 40, and 50 (the wing and flap design is slightly different from the 707 in that there is not a flap 25 setting).

Flaps 20 and 30 are used for takeoff.

Flaps 30, 40, and 50 are used for landing, although Flaps 30 landings are only used for abnormal situations such as loss of hydraulic pressure or similarly, loss of powered rudder.

Both Flaps 40 and 50 approach and landing are considered normal. However, the Command (SAC; later AMC) "standard" is a Flaps 50 (full flap) landing. It provides a stable approach, the lowest approach and landing speed, and a slightly firm landing to dissipate some energy, and it reduces wear and tear on the brakes. However, if a pilot chooses to land with Flaps 40, that is just fine and is actually recommended in gusty crosswind conditions as well as in conditions conducive for wind shear.

With regard to the two things other pilots have told you:

"A B737-200 pilot told me that there were two landing flap settings for that aircraft and that one provided for better handling in gusty or crosswind conditions."

This is true for other aircraft as well. The KC-135 as noted above. On the Airbus A-320, at my operator, Flaps Full (corresponding to 35 degrees) is the standard, "recommended," setting, but we use Flaps 3 (20 degrees) for gusty, crosswind conditions.

"Another pilot told me that he thought that some airlines used a lower flap setting when sufficient in order to reduce the noise footprint of the aircraft during landing."

This is true also, and the lower flap setting uses less fuel during the approach and landing as well.

At my operator, the flight ops folks decided that the difference in the noise level between Flaps 3 and Flaps Full and the difference in fuel burn between Flaps 3 and Flaps Full was not significant and decided to keep Flaps Full as the preferred "recommended" flap setting, unless necessary to use Flaps 3 for operational reasons. You are correct about the noise consideration for military aircraft. Many military bases are not close to urban or residential areas. Using Flaps 40 in the KC-135 for noise consideration was not ever mentioned! Fuel usage in the military is a major consideration, but the AF still wants full flaps for the standard setting (KC-135).

So, to validate your statement, "I would imagine that flaps 50 in the various models of the Boeing 707 created more noise and higher fuel burn."

Yes, of course it did, but not significantly and the Flaps 50 approach and landing (at least in the KC-135) is still the preferred setting. The preferred landing flap setting certainly might have been different for various 707 operators.

Finally, your last question, "Could one go from flaps 25 to flaps 50 without stopping first at flaps 40 or did one need to allow the aircraft to slow at flaps 40 before it was safe to lower the flaps to the 50 setting?"

Yes, in the KC-135 you can go straight from Flaps 20 to Flaps 50 without stopping at the 30 and 40 detents--as long as you don't exceed any of the flap limiting airspeeds--but in normal operations, you would never do this.

First, lowering the flaps in increments allows for a more stable platform and enhances crew "pacing" during the approach sequence. More importantly, however, is the trim function. If you were to go straight from flaps 20 to flaps 50, there would be a considerable amount of trim required while the flaps are in transit--almost a continuous trim requirement--and this would greatly increase the potential for a runaway trim situation and/or a trim motor overheat situation. Regarding trim operation, the preferred technique is to trim in short increments.

Hopefully, there will be some "real" 707 pilots that will provide comment and give you better information.

e38

Thanks so much e38. I really appreciate the time you took to answer the questions. Your replies are simple, clear and very informative. I also appreciate the lack of sarcasm in your responses. I like that you present the "what" "how" and "why" of the different procedures.

What you mention about "trimming" is very understandable although it is a factor that I had not even considered.

I live in a location where I can see the profile of aircraft coming in to land. Most of the airliners I have watched seem to have a somewhat nose high attitude during the approach although I can see, even at a distance, subtle little changes in pitch attitude. The Boeing 707's that I watched seemed to often have a more nose down attitude, kind of like the original DC-9 [the one that lacked leading edge devices.]

I imagine that perhaps wing incidence and flaps have something to do with the 707 nose down attitude on final. But perhaps I am wrong. Since I live near a hot and high airport, maybe what I am seeing is just an anomaly related to the location of the field.

I am not going to pose this as a question since I am a bit ashamed of having burdened you with so many questions. Thanks so much, again, for your responses.

convair880mfan wrote:

I imagine that perhaps wing incidence and flaps have something to do with the 707 nose down attitude on final. But perhaps I am wrong. Since I live near a hot and high airport, maybe what I am seeing is just an anomaly related to the location of the field.

convair880mfan, I am not an aeronautical engineer, but I think your observation is valid and not related to the high and hot nature of Albuquerque airport. My guess is your observation regarding pitch attitude of varying aircraft on final would be similar at other airports.

I think the tendency of aircraft to approach with varying degrees of pitch attitude is a function of high lift devices--trailing edge flaps, and to a greater extent, improvements in leading edge flaps and slats. I'm not completely familiar with the evolution of leading edge flaps and slats on the 707 series, but on the KC-135, we had only small leading edge flaps inboard of the # 1 and 4 engines. As the 707 airframe matured, there were improvements to the leading edge devices, but probably not to the extent of current production aircraft which has resulted in a lower pitch attitude approach profile compared to other aircraft you have observed. You also mentioned the DC-9 series and you are correct, the DC9-10 line--with no leading edge flaps or slats--had a lower pitch attitude on final compared to the DC9-30/40/50 series, and the final approach airspeed was 5 - 10 KIAS faster as well. I think the same can be said of the CRJ 100/200s compared with the CRJ 700/900s, although I have not flown those aircraft.

With regard to your last sentence, "I am a bit ashamed of having burdened you with so many questions."

No, don't be! The questions you ask on Airliners.net are very interesting, appropriate, and thought-provoking.

e38