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So I had this question asked in my recent commercial-pilot checkride:

The DPE asked me about high-density-altitude airports; he specifically asked me if I should add airspeed when I'm on landing approach to a high-density-altitude airport. My total understanding is that the ground roll and landing roll would be affected, as well as the climb, but I've never heard about landing speed being affected; I've been looking in books and researched on the web but I can't get a solid answer.

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Your $v_\mathrm{ref}$ does not depend on density altitude since it is given in Indicated Airspeed, which already accounts for density effects. However, the True Airspeed and therefore also Groundspeed will be higher at a higher density altitude, resulting in more runway required to stop.

The Flight Safety Foundation has a nice summary of factors influencing $v_\mathrm{ref}$:

Factors Affecting the Final Approach Speed

The following airspeed corrections usually are not cummulative; only the highest airspeed correction should be added to VREF (unless otherwise stated in the AOM/QRH):

  • Airspeed correction for wind;
  • Airspeed correction for ice accretion;
  • Airspeed correction for autothrottle speed mode or autoland; or,
  • Airspeed correction for forecast turbulence/wind shear conditions.

Gross Weight

Because VREF is derived from the stall speed, the VREF value depends directly on aircraft gross weight.

The AOM/QRH usually provides VREF values as a function of gross weight in a table or graphical format for normal landings and for overweight landings.

(FSF ALAR Briefing Note 8.2 - The Final Approach Speed)

Altitude, Density Altitude or Pressure are not listed as factors affecting $v_\mathrm{ref}$.

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