B737 All Flaps Up landing. Use of Autobrake Setting or not?
Discussion arose during a 737 simulator session on autobrake use, where some operators mandate use of autobrakes for every landing.
The example of an all flaps up landing came into the conversation where study of the landing length required indicated it was indeed marginal. The consensus was that it would be wise to have the autobrakes set to Max. In fact, criticism would almost certainly be levelled at the pilot if he chose not to use autobrakes. This would be backed up with reference to the FCTM that says: "Boeing recommends that whenever runway limited, using higher than normal approach speeds, landing on slippery runways or landing in a crosswind, the autobrake system be used."
Then someone pointed out that the QRH (Advisory Information, Non-Normal Configuration Landing Distance Dry Runway) that lists the different landing configurations, also contains a footnote that states the distances assume maximum manual braking and maxiximum reverse thrust when available on the operating engines.
As maximum manual braking gives better deceleration than Max autobraking, it could be argued this footnote implies that autobraking should not be used since deceleration is less than with maximum manual braking. In turn this would suggest the landing distance numbers for Non-Normal Configuration Landing Distance are invalid if autobrakes are used? At first glance, most pilots would indeed select an autobrakes setting for an all flaps up landing on a limiting length runway. Paradoxically, this precaution (some would call it good airmanship) could well lead into the potential for an over-run - since the landing length figures are based upon the much harsher braking available through manual braking, rather than automatic braking. In each case maximum reverse thrust is assumed.
Your thoughts are welcomed.