Fundamentals Skills of Instrument Flying
There are a couple of questions on this topic on the knowledge test, so getting the terminology right can come in handy. From the Instrument Flying Handbook:
During attitude instrument training, two fundamental flight skills must be developed. They are instrument cross-check and instrument interpretation, both resulting in positive aircraft control. Although these skills are learned separately and in deliberate sequence, a measure of proficiency in precision flying is the ability to integrate these skills into unified, smooth, positive control responses to maintain any prescribed flightpath.
Instrument Cross Check
Cross-checking is the continuous and logical observation of instruments for attitude and performance information.…Although no specific method of cross-checking is recommended, those instruments that give the best information for controlling the aircraft in any given maneuver should be used. The important instruments are the ones that give the most pertinent information for any particular phase of the maneuver. These are… usually the instruments that should be held at a constant indication. The remaining instruments should help maintain the important instruments at the desired indications.
Selected Radial Cross-Check
When the selected radial cross-check is used, a pilot spends 80 to 90 percent of flight time looking at the attitude indicator, taking only quick glances at the other flight instruments… With this method, the pilot’s eyes never travel directly between the flight instruments but move by way of the attitude indicator.
Inverted-V Cross-Check
In the inverted-V cross-check, the pilot scans from the attitude indicator down to the turn coordinator, up to the attitude indicator, down to the VSI, and back up to the attitude indicator.
Rectangular Cross-Check
In the rectangular cross-check, the pilot scans across the top three instruments (airspeed indicator, attitude indicator, and altimeter), and then drops down to scan the bottom three instruments (VSI, heading indicator, and turn instrument).
Common Cross-Check Errors
Fixation, omission, and emphasis on a single instrument, instead of on the combination of instruments necessary for attitude information.
Instrument Interpretation
The second fundamental skill… begins by understanding each instrument’s construction and operating principles. Then, this knowledge must be applied to the performance of the aircraft being flown, the particular maneuvers to be executed, the cross-check and control techniques applicable to that aircraft, and the flight conditions.
Airplane Control
For each maneuver, learn what performance to expect and the combination of instruments to be interpreted in order to control aircraft attitude during the maneuver. This topic deserves an entire post, Aircraft Control During Instrument Flight
The Importance of the Instrument Cross Check
SW Aviator
goes into detail about the importance of the cross-check for detecting failed instruments: The instrument crosscheck is an important backup measure that prevents a spatial-disorientation/unusual-attitude disaster by increasing the chance of early recognition of a failed instrument. Its importance only becomes apparent when an instrument actually fails.
The failures that an instrument crosscheck is designed to detect cannot be demonstrated in flight. Simulators and computer training devices offer about the only opportunity to realistically train for gradual and/or unexpected instrument failures. Puckering liability issues dictate against installing a valve that can block the vacuum lines to simulate vacuum failure, and usually there are no switches to surreptitiously flick to disable an electric instrument. Yet the importance of mastering the transition is apparent in several studies that have shown that 1) it takes a significant amount of time, measured in minutes, for pilots just to recognize an instrument failure, and that 2) this is plenty time to get into real trouble. Coping with a failed instrument by using a partial-panel scan is an entirely different problem from recognizing the failure: the same pilots flew well enough in partial-panel mode when the instrument failure was known, suggesting that it is detection of the failure that is confusing, and that training for it is difficult, deficient, or both.
Attitude Instrument Flying Video
Knowledge Test Questions
What is the correct sequence in which to use the three skills used in instrument flying?
Cross-check, instrument interpretation, and aircraft control.
What are the three fundamental skills involved in attitude instrument flying?
Cross-check, emphasis, and aircraft control.
What is the third fundamental skill in attitude instrument flying?
Aircraft control.
What is the first fundamental skill in attitude instrument flying?
Instrument cross-check.