Avionics Multiple Choice Questions on “Carrier Landing Systems”.
1. The relative speed of the aircraft with respect to the carrier deck is _________
a) Lower
b) Greater
c) Zero
d) Indifferent
Answer: a
Clarification: Jet aircraft approach the carrier deck with at airspeeds up to 125 knots. Their speed relative to the deck is lower due to the “wind over the deck,” which is normally about 30 knots.
2. What is the inclination of the glide slope with respect to the moving flight deck?
a) 3°
b) 5°
c) 3.5°
d) 4°
Answer: d
Clarification: The approach path, often called the glide slope, is in the vertical plane containing the runway center line and is inclined 3.5° relative to the sea at the touchdown point and 4° relative to the moving flight deck.
3. Which of the following causes a “burble” at the threshold and along the glide path?
a) High speed landings
b) Low visibility
c) Heaving motion of ship
d) Steady state wake
Answer: d
Clarification: Steady state wake caused by the relative wind over the ship’s deck and around the superstructure, Which causes a “burble” at the threshold and the glide path.
4. Wake perturbations are caused by ________
a) High speed landings
b) Low visibility
c) Heaving motion of ship
d) Steady state wake
Answer: c
Clarification: Wake perturbations, due to the ship’s angular motions and heave, causing fluctuations with standard deviations of 2 ft/sec(horizontal) and 4 ft/sec (vertical) about the steady state wake.
5. Aircraft executing missed approach from low altitude is called as ____________
a) Bolter
b) Faultie
c) Ranger
d) Dropper
Answer: a
Clarification: An aircraft executing a missed approach from low altitude is called a bolter. Bolters fly to a Tacan- defined holding point that moves with the aircraft carrier.
6. The ACLS can land an aircraft in zero visibility conditions.
a) True
b) False
Answer: a
Clarification: The ACLS is capable of landing an aircraft “hands-off,” giving the U.S. Navy an operational capability in zero visibility conditions. It can land an airplane more accurately than an average pilot.
7. Which of the following is an optical landing aid used in aircraft carriers?
a) ACLS
b) FLOLS
c) SPN-41
d) SPN-46
Answer: b
Clarification: FLOLS or the Fresnel lens optical landing system consists of an array of 5 Fresnel lens showing the pilot a yellow spot that moves relatively to a lighted green horizontal reference bar.
8. Why is heave motion of the carrier not corrected in the FLOLS?
a) Two aircraft use simultaneously
b) Atmospheric fluctuations
c) Too random motion
d) Not economical
Answer: a
Clarification: Lens pointing angles can be adjusted to a quadratic function of heave and can be compensated. This compensation is not implemented because the “meatball” is often shared by two aircraft on final approach simultaneously.
9. What is the frequency band used by the ACLS?
a) Ka band
b) S band
c) C band
d) E band
Answer: a
Clarification: Two electronic instrument landing systems are found o all large U.S. carriers. Th ACLS involves two identical conically scanned Ka band radars set aft of the island about 125 and 135ft above the water line.
10. Which of the following is false with respect to ACLS?
a) Zero visibility landing is possible
b) Uses Ka band radars
c) Compensated for carrier roll, heave and pitch
d) Only handle one aircraft at a time
Answer: d
Clarification: The two identical conically scanned radar antennas can track two aircraft simultaneously and, if desired, can uplink guidance signals to autopilots.
11. What is added to SPN-42 to eliminate wandering of the echo skin?
a) AESA
b) Aircraft beacon
c) PESA
d) Helical antenna
Answer: b
Clarification: The SPN-42 was retrofitted with a small X-band parabola when aircraft beacons were added to eliminate errors caused by wandering of the echo skin.