Aircraft Measurements Performance Evaluation and Daily Instrument Ratings

Research Aircraft Facility Evaluation

A performance evaluation scoring scheme has been devised. The maximum score is 100 points. For full points, the aircraft measurements must appear "reasonable" for the entire flight. No points will be awarded if the aircraft is unable to fly a requested mission or if the data system is not capable of recording. If a sensor or measurement device fails intermittently during a flight, but still appears usable for most of the flight, half credit will be allowed. It is the responsibility of the Aircraft Mission Scientist to complete the form.

The evaluation criteria are intended for the routine screening of data. Many of the measurements permit either in-flight or post flight intercomparisons. The computer processing of the data tapes after each flight will include intercomparisons among the sensors measuring the same parameter. Where possible, comparisons will be made with tower or rawinsonde data. Discrepancies outside the tolerances listed below will result in the deduction of points on the evaluation form. The procedures for routinely evaluating each sensor's performance are as follows:

a. 2D-C and 2D-P: The real-time and post-flight processed particle images will be examined during cloud penetration segments and this should provide a clear indication of the performance of the 2D probes. Daily pre-flight checks using water sprays or wire devices will be performed.

b. FSSP: Routine evaluation will be based on proper response of the instrument during pre-flight inspections when droplets from a nebulizer are sprayed through the sample volume.

c. Johnson-Williams Liquid Water Sensor: The JW should agree with the FSSP in regard to the presence of liquid water contents greater than 0.2 g/m3. The relative agreement is more appropriate than the absolute agreement which can vary between 50 and 100%. A comparison between the FSSP and JW liquid water contents will be part of the data processing program.

d. Rosemount and Reverse Flow Temperature Sensors: These sensors will be compared to each other during the post-flight processing. Portions of the flight during which the two sensors differed by more than 2C will be noted. (Note: discrepancies are expected in-cloud and immediately after cloud penetrations because of the wetting of the Rosemount sensor). The pre-flight inspection will include a temperature comparison with the tower measurement.

e. Dew Point Temperature Sensor: This sensor will be checked during the pre-flight inspection with a dry and wet bulb thermometer. The dewpoint will also be compared to tower and rawinsonde measurements. The accepted tolerance is 2C.

f. Static Pressure Measurement Sensors: These measurements will be compared to a separate precision aneroid barometer as part of the the pre-flight inspection. The measurements will also be intercompared during the post-flight data processing. The accepted tolerance is 2mb.

g. The INS, VOR/DME, gust probe, iceparticle counter, aerosol sampler, weather radar, transponder, intercom, video, and camera performance will be assessed during the flight. Post-flight data processing output will be routinely inspected to assure data quality.