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Difference between revisions of "Coffin Corner"

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As an aircraft climbs towards the altitude that defines its coffin corner, the margin between stall speed and critical Mach number becomes smaller and smaller until the Flight Envelope boundaries intersect. At this point, any change in speed would result in exceeding one or the other of the limits. In the most critical case, turning the aircraft could result in exceeding both limits simultaneously as, in a turn, the inside wing slows down whereas the outside wing increases speed. Likewise, encountering [[Turbulence|turbulence]] could result in a "beyond limits" change in airspeed.
 
As an aircraft climbs towards the altitude that defines its coffin corner, the margin between stall speed and critical Mach number becomes smaller and smaller until the Flight Envelope boundaries intersect. At this point, any change in speed would result in exceeding one or the other of the limits. In the most critical case, turning the aircraft could result in exceeding both limits simultaneously as, in a turn, the inside wing slows down whereas the outside wing increases speed. Likewise, encountering [[Turbulence|turbulence]] could result in a "beyond limits" change in airspeed.
  
In commercial and general aviation operations, flight at altitudes approaching coffin corner is generally avoided. Compliance with the aircraft manufacturer charted maximum altitude, for the existing weight and temperature, will normally ensure that adequate buffet margins for both the high and low speed boundaries are maintained. In the event that turbulence is encountered or forecast, the flight altitude should be reduced to ensure that buffet margins are not compromised.
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In commercial and general aviation operations, flight at altitudes approaching coffin corner is generally avoided. Compliance with the aircraft manufacturer's charted maximum altitude, for the existing weight and temperature, will normally ensure that adequate buffet margins for both the high and low speed boundaries are maintained. In the event that turbulence is encountered or forecast, the flight altitude should be reduced to ensure that buffet margins are not compromised.
  
 
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Revision as of 19:18, 30 November 2013

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Description

In aviation, coffin corner (or Q corner) refers to the point at which the Flight Envelope boundary defined by a high incidence stall intersects with that defined by the critical Mach number. In other words, coffin corner occurs when, for a specific gross weight and G-force loading, the aircraft has climbed to an altitude where the speed differential between the onset of low speed stall buffet and the onset of high speed Mach buffet approaches zero.

As an aircraft climbs towards the altitude that defines its coffin corner, the margin between stall speed and critical Mach number becomes smaller and smaller until the Flight Envelope boundaries intersect. At this point, any change in speed would result in exceeding one or the other of the limits. In the most critical case, turning the aircraft could result in exceeding both limits simultaneously as, in a turn, the inside wing slows down whereas the outside wing increases speed. Likewise, encountering turbulence could result in a "beyond limits" change in airspeed.

In commercial and general aviation operations, flight at altitudes approaching coffin corner is generally avoided. Compliance with the aircraft manufacturer's charted maximum altitude, for the existing weight and temperature, will normally ensure that adequate buffet margins for both the high and low speed boundaries are maintained. In the event that turbulence is encountered or forecast, the flight altitude should be reduced to ensure that buffet margins are not compromised.

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