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Following up on my previous question about the typical vertical speed during the touchdown, I am now curious about the typical touchdown angle.

Airliners touch down with the main landing gear first, and only then the nose wheel. Hence there is some angle between the runway and the aircraft's body longitudinal axe. Let's assume that the runway is flat and that there is no slope in the runway.

Of course, the angle depends on many, many factors. It's theoretical maximum would be limited through a tailscrape event - and since aircraft are different in length, there is no general answer to this one. Theoretical minimum would be 0 degrees (or less, but then we have a nose wheel first landing). But, as highlighted in answers to my previous question, is there any information in operating manuals about typical angles, or can pilots provide some insight into which angle they are trying to achieve during touchdown?

Besides the typical angle, is there an optimum angle for any reason?

Again, I am not interested in the approach, only the touchdown after the flare.

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  • $\begingroup$ One primary restriction is called "the angle on the deck". This limitation prevents them from scraping the tail, and on some aircraft with engines in the tail (i.e. fuselage blocks the 727 #2 engine) keeps the air stream straight enough for full power. The B727, DC10, and most stretch versions of aircraft will have deck angle limitations. Inlet air angle was among several problems of the Comet, this was attributed to one crash and several near catastrophes. $\endgroup$ – jwzumwalt Jan 13 '18 at 14:27
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(Source: 744 FCTM)

The relevant text reads:

Airplane body attitudes are based upon typical landing weights, flaps 30, VREF 30 + 5 (approach) and VREF 30 + 0 (landing), and should be reduced by 1° for each 5 knots above this speed.

Typical landing flare times range from 4 to 8 seconds and are a function of approach speed.

Initiate the flare when the main gear is approximately 30 feet above the runway by increasing pitch attitude approximately 2° - 3°. This slows the rate of descent.

So for one of the largest, a delta of 2-3° is achieved in 4 to 8 seconds. As the text shows, the attitude varies based on speed, flaps, etc., so we can take the delta as both the optimum and typical value.

I checked the 777-200 FCTM, the values are different. And of course the smaller the plane, say a 737, the later the flare is initiated due to the smaller [and later] the ground effect.

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