9 questions on this topic, recalled by candidates after DGCA sittings between 2021 and 2026. Together they were asked 14 times; the most repeated come first. Pick a year to see only what was asked that year.
B. Decreases
A high density altitude means the air is as thin as it would be much higher up in the ISA. Less dense air gives less lift and less engine power - the hot, high aerodrome problem.
A. Higher
Cold air is denser than warm air, so the cold polar surface air is denser than the warm equatorial air.
B. Lower
The picture reverses aloft. The polar air is so dense that most of its mass is packed low down, so above about 8 km there is less air left over the poles than over the equator - density is lower there.
B. The ISA altitude at which the prevailing density occurs
Density altitude is the height in the standard atmosphere that has the same density as the air you are actually in. The first option describes pressure altitude.
B. Lower
Water vapour (molecular weight 18) is lighter than dry air (about 29). Replacing some air with vapour lowers the density, so humid air gives poorer take-off performance.
A. More
Rain means a warm, humid, low-pressure day with a wet runway: lower air density cuts engine and wing performance, and the wet surface lengthens the stop. Both push the runway length required up.
Our independent check could not confirm this answer from the official sources we hold; treat it with care and confirm with your instructor.
B. The ISA standard temperature for that level
Density altitude is pressure altitude corrected for non-standard temperature. When the actual temperature equals ISA, there is nothing to correct and the two are the same.
C. All of these
Density falls as altitude rises (lower pressure), as the air warms (it expands) and as humidity rises (water vapour is lighter than the nitrogen and oxygen it replaces). All of these give less dense air.
A. 1.225 kg/m3
The ICAO Standard Atmosphere fixes sea level at 15 °C, 1013.25 hPa and a density of 1.225 kg/m3. Density falls off with height much as pressure does, roughly halving by 22 000 ft, and it is density rather than pressure alone that decides engine power, lift and true airspeed.
These are candidates' recollections, not official DGCA papers: wording can differ from the paper as set. Every answer was checked against the DGCA CARs, AIP India, ICAO documents or worked calculation (independent check completed 17 Oct 2026). Spotted a mistake? Tell us and we will check it against the source.