ATPL Instrument Flight Rules and Approaches 1 — Questions and Answers
Question 1: Decision Altitude (DA) differs from Decision Height (DH) in that:
- DA is used for non-precision approaches only
- DA is referenced to mean sea level while DH is referenced to threshold elevation (Correct answer)
- DH is used for CAT I only, DA for CAT II/III
- DA and DH are identical terms
Correct answer: DA is referenced to mean sea level while DH is referenced to threshold elevation
Decision Altitude is referenced to mean sea level (MSL) while Decision Height is referenced to the height above the runway threshold — both mark the point where a missed approach must be initiated if visual contact is not established.
Question 2: The ILS glide slope nominal descent angle is:
- 2.0°
- 2.5°
- 3.0° (Correct answer)
- 3.5°
Correct answer: 3.0°
The standard ILS glide slope angle is 3.0°, providing a normal descent gradient for most aircraft during the final approach segment.
Question 3: Minimum Descent Altitude (MDA) is used on which type of approaches?
- Precision approaches (ILS, GLS)
- Non-precision approaches (VOR, NDB, LNAV) (Correct answer)
- CAT II/III approaches
- Visual approaches
Correct answer: Non-precision approaches (VOR, NDB, LNAV)
MDA is used on non-precision approaches where vertical guidance is not provided — the pilot descends to the MDA and flies level until the runway environment is in sight or the missed approach point is reached.
Question 4: What does 'LNAV/VNAV' on an RNAV approach chart indicate?
- Localizer-only approach with barometric altitude
- Lateral navigation with vertical guidance using barometric altitude — a precision-like approach (Correct answer)
- A fully augmented GPS approach equivalent to CAT III
- An approach requiring ILS and RNAV simultaneously
Correct answer: Lateral navigation with vertical guidance using barometric altitude — a precision-like approach
LNAV/VNAV is an RNAV approach type using lateral GPS guidance and barometric vertical navigation, providing a DA rather than MDA for a precision-like approach without the full accuracy of LPV.
Question 5: Required Navigation Performance (RNP) AR approach procedures require:
- Standard GPS receivers certified to TSO-C129
- Advanced FMS with on-board monitoring and alerting capability meeting specific RNP values (Correct answer)
- Dual VOR receivers with DME
- ILS Cat II equipment and certification
Correct answer: Advanced FMS with on-board monitoring and alerting capability meeting specific RNP values
RNP AR (Authorization Required) procedures require a navigation system capable of monitoring its own accuracy and alerting the crew if performance degrades below required levels, enabling curved approaches and very low minimums.
Question 6: When established on the ILS localizer, what does a full-scale localizer deflection indicate?
- The aircraft is on the centerline
- The aircraft is approximately 2.5° from centerline (Correct answer)
- The aircraft is outside the protection area
- The aircraft has intercepted the glide slope
Correct answer: The aircraft is approximately 2.5° from centerline
A full-scale localizer deflection indicates approximately 2.5° angular deviation from the centerline, though actual linear distance depends on distance from the runway threshold.
ATPL Instrument Flight Rules and Approaches 1
Decision Altitude (DA) differs from Decision Height (DH) in that: