Primary Flight Displays in the T-38C: When Do Differences Among Displays Become Inconsistencies

摘要

In the 1980s the US military settled on counterpointers, or dials, as the standard gauge for display of airspeed and altitude in a head-up display (HUD). This format is now making its way into production aircraft, one of which is the T-38C, a US Air Force (USAF) fighter jet trainer. The T-38C is unique in possessing three primary flight displays: a head-down primary flight display (PFD) suite, a HUD in Military Standard (MIL-STD) emulation mode, and the same HUD in F-16 emulation mode. Differences among these displays include color, scale, and gauge format (e.g., tapes vs. dials). A study was conducted as part of the Air Force's primary flight display endorsement process to determine if differences among these displays represent inconsistencies that might have practical impact on pilot performance, situation awareness, or workload. Sixteen T-38 pilots flew maneuvers designed to test spatial orientation and trend perception. Maneuvers were flown with each PFD alone and in two transition conditions: from the MIL-STD HUD to the HDD, and from the F-16 HUD to the HDD. Flight performance data were collected and pilots also rated situation awareness (SA) and workload. Three senior USAF Instructor Pilots (IPs) graded each maneuver. No practically significant differences were found in performance: differences among conditions were small and not operationally relevant. Pilots actually rated SA higher and workload lower when using the F- 16 HUD, even though HUD and HDD gauge formats differed when using this display. Pilots also rated the F-16 HUD higher than the MIL-STD for facilitating an efficient crosscheck, not presenting conflicting cues, and using an intuitive data manipulation scheme. The results support a conclusion that consistency within a PFD is more important than consistency across head-up and head-down PFDs: differences in location, color, and display medium may facilitate perceptual and attentional separation of the information displayed.