Flight Data Recording Questions and Answers

Answer: C

Correct answer: Insults arrive one after another

A real accident does not present the tests separately. The unit decelerates, is crushed by structure, burns in the fuel fire and then lies submerged - each condition acting on a module already damaged by the last.

Testing the same unit in sequence reproduces that accumulation. A module might survive fire alone and fail it after being crushed, its seals already broken. Passing the tests on four fresh units would prove nothing about the case that matters.

Answer: D

A few hundred megabits is trivial for modern memory, so the practical limits are now wiring, sensors and certification rather than capacity. That is precisely why parameter counts could grow from a handful to hundreds.

Answer: A

Correct answer: The quick access recorder against the crash protected units

Read the two columns together. Three rows are crash protected and used for accident investigation; the quick access recorder is neither, existing for routine safety monitoring.

That is a difference in purpose rather than in degree. The crash-protected units answer what happened on one flight, and are read perhaps once in the aircraft's life; the QAR answers what is happening across thousands of flights, and is read after every one. The deployable recorder differs from the others only in how it is recovered.

Answer: B

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the second is the reason for the first. The recorder writes on a loop, so each further minute of running overwrites a minute of the oldest material held.

Where the relevant events lie near the start of the retained period, leaving the unit powered destroys the evidence - and the loss is irreversible. Pulling the breaker stops the loop, and operators' procedures require it after a serious incident. The extension of voice retention to two hours and then 25 addresses the same problem at source.

Answer: C

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the second is the reason for the choice. Sea water conducts, and radio frequencies are attenuated within a very short distance of the surface - nothing from a submerged beacon reaches a receiver or a satellite.

Sound propagates well, so the beacon emits an acoustic pulse at 37.5 kHz that a hydrophone detects at a mile or two. It is the medium that dictates the physics, not a preference of the designers.

Answer: D

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the second gives both halves of the reason. Frame capacity is fixed, so the sampling budget must be allocated; and parameters change at speeds differing by orders of magnitude.

Spending eight samples a second on fuel quantity would waste bandwidth that vertical acceleration needs to capture a hard landing. Matching the rate to the rate of change is what lets a modest data rate carry hundreds of parameters usefully.

Answer: A

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the second is precisely why the first holds. The mandatory requirement exists so that data survives an accident, and a recorder in an ordinary avionics enclosure would not.

The QAR records the same parameters and is fitted almost universally, but it answers a different question - what is happening across many flights - and its accessibility is the whole point of it. Recording the right data is not sufficient; surviving to be read is the requirement.

Answer: B

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the second is the mechanism. Salt residue is conductive, so applying power to an uncleaned module can short tracks that are otherwise intact, and current through an electrolyte drives corrosion far faster than immersion alone.

Cells that would have been readable after cleaning and drying are then lost, and there is no second attempt at a unique record. That is why the sequence is fixed: assess, clean, dry, and only then attempt a readout.

Answer: C

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the second is why the anchoring is necessary. A wrong scaling factor does not produce nonsense: a gain error changes the amplitude while preserving the shape, and an offset shifts the whole trace - both look entirely plausible.

Only comparison with independently known events exposes them: radar returns, radio recordings, the documented times of actions. Errors that announced themselves would need no such check; it is precisely the plausible ones that make it essential.

Answer: D

Correct answer: A is true but R is false

The assertion is correct: solid-state memory removed the capacity constraint, and parameter counts grew markedly once it did.

The reason inverts the comparison. Magnetic tape offered less usable capacity, not more, and brought a transport mechanism vulnerable to impact and fire. It was the tape era that kept parameter lists short. A true assertion with a false reason, so each must be judged separately before they are compared.