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Crossover altitude indication on a vertical situation display Disclosure Number: IPCOM000236599D
Publication Date: 2014-May-05
Document File: 2 page(s) / 107K

Publishing Venue

The Prior Art Database


This is a design proposal for displaying the Crossover Altitude on the Vertical Situation Display

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For background performance calculations there is an altitude calculated at which the target Mach and CAS (Calibrated Airpseed) equivalent True Airspeed values are equal. This altitude is called the crossover altitude. This is also the altitude at which the visible speed tape will switch from CAS to Mach in climb and Mach to CAS in descent.


Currently there is no indication to the pilot as to when his speed tape will switch between speed types, or if it will at all. In descent this can particularly be an issue as at a constant Mach and decreasing altitude the aircraft will be accelerating, but when the speed target switches to CAS the aircraft will begin decelerating.

Technical Discussion

In order to show the pilot when his speed targets and speed tape will switch types, a new indication will be added the Vertical Situation Display. This will allow him to see when to expect a change in speed targets and expect to feel the acceleration change in his aircraft. Figure 1 and Figure 2 show two proposed indications.

Figure 1 VSD Proposal 1

Figure 2 VSD Proposal 2

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Figure 3 VSD Climb and Descent with Proposal 2

Related Documents/References


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