Cockpit Display Systems Questions and Answers

Answer: C

Correct answer: 0.01

The expected number of events is the rate multiplied by the exposure:

\[ 10^{-9} \times 10^{7} = 10^{-2} = 0.01 \]

So in ten million flight hours, one hundredth of an event is expected. The \( 10^{-9} \) per flight hour figure is the certification target for a catastrophic failure condition, and displaying misleading primary flight information is classified at that level - which is why display systems carry the most demanding software assurance level and extensive independent monitoring.

Answer: D

Correct answer: \( 10^{-8} \)

For independent events the joint probability is the product:

\[ 10^{-4} \times 10^{-4} = 10^{-8} \]

The result is only as good as the independence assumption, which is the real lesson. Two displays sharing a symbol generator, a power supply, a cooling duct or a software load are not independent, and a common cause can defeat the calculation entirely. This is why redundancy is pursued through dissimilarity and segregation, not merely by fitting two of something.

Answer: A

Correct answer: 6.7 nautical miles per inch

Divide the range displayed by the screen dimension over which it is drawn:

\[ \frac{40\ \mathrm{nm}}{6\ \mathrm{in}} = 6.7\ \mathrm{nm\ per\ inch} \]

Scale changes as the crew selects a different range, and with it the apparent density of the picture: at a long range the whole route fits but individual waypoints crowd together, while at a short range the detail is legible but the aircraft is soon off the end. Range selection is therefore itself a decluttering action.

Answer: B

Correct answer: 2.0 seconds

Multiply the dwell time by the number of instruments:

\[ 5 \times 0.4 = 2.0\ \mathrm{seconds} \]

A two second cycle means any one parameter is unobserved for nearly two seconds at a time, which is the human factors argument behind the basic T layout and behind integrated displays generally: placing related information close together shortens the scan, and combining several parameters into one picture - the flight path vector, for instance - removes items from the loop altogether.

Answer: C

Correct answer: Both Statement I and Statement II are correct

Both statements are correct and the second is the reason the first was done. The basic T - attitude centrally, airspeed to its left, altitude to its right, heading below - was carried onto glass displays essentially unchanged.

The purpose was to preserve the trained scan. A pilot who learned to move between those positions on mechanical instruments finds the same information in the same places on a glass panel, so the skill transfers directly and the transition training is about the new capabilities rather than about relearning where to look.

Answer: D

Correct answer: Both Statement I and Statement II are correct

Both statements are correct and the second explains the first. A blank or flagged display announces its own failure: the crew knows the information is gone and turns to the standby instruments or the other pilot's display.

A plausible but wrong value announces nothing, and may be acted upon. Certification reflects this asymmetry - misleading primary flight information is classified as catastrophic and allocated a probability target of \( 10^{-9} \) per flight hour, while loss of the same information is treated less severely, which is why display systems are built to fail conspicuously rather than quietly.

Answer: A

Correct answer: Both Statement I and Statement II are correct

Both statements are correct and the second gives the distinction. An enhanced vision system images the real scene with an infrared, millimetre wave or low-light sensor, so it can reveal a vehicle on the runway or an unlit obstruction. A synthetic vision system draws the scene from a terrain and obstacle database, positioned by the navigation solution, so it gives a clean picture in any weather but shows only what the database holds.

They are therefore complementary rather than interchangeable, and combined vision systems present the two together - the synthetic picture as a background with the sensor image overlaid.

Answer: B

The first is correct and the second is the approach dark cockpit rejects. Lighting normal states buries the abnormal in a field of lit legends, which is exactly the failure mode that the dark cockpit principle was devised to avoid.

Answer: C

Correct answer: Both Statement I and Statement II are correct

Both statements are correct and the second explains the first. Head-up display symbology is collimated so the virtual image lies at optical infinity, matching the focus of the distant outside scene.

Without collimation the eye would have to accommodate between symbols a few feet away and a runway a mile away, taking a fraction of a second each time and defeating the purpose of putting the information in the forward field of view. Collimation also makes the symbology insensitive to small head movements, which is what allows conformal symbols to stay registered with the world.

Answer: D

Correct answer: Statement I is incorrect but Statement II is correct

Statement I is incorrect. Adding information does not always improve the picture, and beyond a point it degrades it.

Statement II is correct and is why: each additional symbol competes for attention with every other, so the time to find a needed value rises and the chance of missing something important rises with it. The effect bites hardest at high workload, when the margin is least. Good display design is therefore as much about what to leave out, or to suppress by flight phase, as about what to show.