Runway Analysis Chart

[MauleSkinner]

Any insight into why the reference Weight used to deduct penalties from on Takeoff, Climb, Approach Climb and Landing Climb is in excess of Maximum Structural Weight??

Because they’re separate from the structural limit, and if you start subtracting the penalties from the structural limit you’d be penalizing yourself excessively.

Maximum takeoff weight is generally going to be the lowest of structural, climb, brake energy, and runway limit weights (plus one or two others in some aircraft.) you calculate all of those limit weights and take the lowest of them, which in some cases will be the structural limit.

 

[fasteagle]

Because they’re separate from the structural limit, and if you start subtracting the penalties from the structural limit you’d be penalizing yourself excessively.

Maximum takeoff weight is generally going to be the lowest of structural, climb, brake energy, and runway limit weights (plus one or two others in some aircraft.) you calculate all of those limit weights and take the lowest of them, which in some cases will be the structural limit.

Thank you. But with respect to the higher 'reference weight' which for example CDL weight penalties are deducted from for Takeoff

or the 'reference weight' from which penalties for enroute icing or use of wing/cowl anti ice are deducted for Approach Climb and/or Landing Climb

Where do those unusually high reference weights come from? Is there some formula used by the manufacturer to determine such weights??

Also, is there a good source for additional reading about the hierarchy of Takeoff Runway limit codes which would affect/restrict Max Runway Takeoff Weight for a given runway??

 

[Larry in TN]

Where do those unusually high reference weights come from? Is there some formula used by the manufacturer to determine such weights??

They are based on aircraft performance without regard for structural limits. It is the base value from which the adjustments are made. If they stopped at structural weight then the adjustments values would give an answer that was more restrictive than necessary.

Also, structural weights can change. There could be modification, or ADs, etc. that change structural weights and this way the charts wouldn't have to be changed with each change in structural weights.

 

[MauleSkinner]

Where do those unusually high reference weights come from? Is there some formula used by the manufacturer to determine such weights??

As an example, here is the climb limit chart for a particular corporate jet. At 6000 feet and 30 deg C, their example shows a maximum allowable weight to achieve climb requirements at about 14,400 pounds, which is below the structural limit of 16,300 pounds.

On the other hand, at 0 deg C and sea level, it’s off the chart, well above 18,000 pounds. The NOTE says that for takeoff with engine anti-ice ON we need to subtract 1400 pounds from “the weight read from this graph.” The maximum weight we can read from the graph is 17,900 pounds (the lines end before 18,000 pounds,) so 17,900-1400=16,500 pounds. Still above structural, so the structural limit is limiting rather than climb.




The Runway Analysis provider simply programs airplane charts into a different format.