REG NASA-LLIS-1628 Lessons Learned - C-17 Flight Tests.pdf

1、Lessons Learned Entry: 1628Lesson Info:Abstract: Significant time delays in the display of real time flight test data on a “lap top” computer have been observed. Description of Driving Event: C-17 Flight Tests Lesson(s) Learned: When using “lap top” Personal Computers (PCs) for real time data monito

2、ring the user should be aware that the PCs main processor can be significantly slowed down when the computer is operated on internal battery power as contrasted to external power. Some PCs are designed to reduce their processing speed when operated on the internal battery in order to increase the ba

3、ttery powered operational time. When monitoring real time data the slowed processor can result in a significantly delayed monitor display of information. The delayed display can be particularly critical if the PC is being used to monitor real time safety of flight information. Delays of as much as t

4、wo seconds have been observed. This is enough time for a C-17 airplane to traverse from 0 to 30 degrees of bank angle. Recommendation(s): Users of “lap top” computers for monitoring real time data need to understand the update speeds of the information they are observing. If the user is monitoring s

5、afety of flight data they must understand the update rate of the information they are observing. Unless a user has a complete understanding of the update rate for an internal battery powered PC external power supplies should be used. When monitoring real time safety critical data understanding of th

6、e complete (end to end) data acquisition update rate inclusive of the monitor used is mandatory. Evidence of Recurrence Control Effectiveness: The C-17 Test Force has successfully used external power supplies, and external time code generators for comparison with the PCs time. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Documents Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): N/AAdditional Info: Approval Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-