An Uncomfortable Place


A pilot assigned to the Stingers of Strike Fighter Squadron One One Three (VFA-113) is directed into launch position. (U.S. Navy photo by Mass Communication Specialist 2nd Class Aaron Burden)

A pilot assigned to the Stingers of Strike Fighter Squadron One One Three (VFA-113) is directed into launch position. (U.S. Navy photo by Mass Communication Specialist 2nd Class Aaron Burden)


It was going to happen eventually. All good things come to an end, and my incredibly lucky run of avoiding display issues at the boat came to a screeching halt on a “pinky” cat shot two weeks into our composite training unit exercise (COMPTUEX).

The master caution went off as the jet started to fly away and the light in the gear handle accompanied with a continuous beeping tone immediately caught my attention. Worried that my gear had not come up, I tried to double check my airspeed to find that the airspeed box in the heads up display (HUD) was empty. Not entirely sure what was wrong at the time, I continued to climb until I was sure I was nowhere near the water. Passing 5,000 feet, the radar altimeter (RADALT) kicked off and I lost my altitude reference as well. Glad that I still had some horizon left, I called for assistance and started to cycle through my displays. I had an AIR DATA caution and an associated air data computer (ADC) MUX fail on the BIT page. My worst nightmare of a standby recovery at the boat was finally occurring and to make matters worse the marine layer was moving in and the moon was nowhere in sight.

According to NATOPS, the ADC receives inputs from numerous sources and calculates accurate air data and magnetic headings. Information is supplied to the mission computers, the altitude reporting function of the IFF, engine controls, environmental control system, landing gear warning, and the fuel pressurization and vent system. From a piloting standpoint, the loss of airspeed and barometric (BARO) altitude is disconcerting but to make matters worse, the velocity vector may become inaccurate after approximately 10 minutes and the procedures call for the ATT switch to be placed in standby (STBY). For all of us who have become velocity vector cripples, this is a major degradation of one’s scan within the cockpit. The landing signals officer (LSO) sight picture is affected as well since the outside AOA indexers do not function.

I was directed to use ground speed as an airspeed reference until I could get my gear down and use the “E” bracket for AOA control. The decision was made for me to return with the current recovery, so I had plenty of gas to fly around dirty. As my hopes of being mercifully diverted to North Island dwindled, I requested that a tanker join on me prior to descending through what had become a black abyss. Standby instruments function normally with an ADC failure, but flying steam gauges as my sole altitude reference until 5,000 feet was not my idea of a good time.

With the tanker on my wing, I found it easier to retain the lead vice flying form. It gave me a chance to get used to the standby sight picture on the HUD and take things at my own speed. My TACAN was intermittent and my tanker escort did an outstanding job of driving me around and backing me up on my altitude and rate of decent. He told approach that he would set me up on the straight in and that they could start directing us once we were lined up. Thankfully, the ILS was still functioning which significantly enhanced my reference points. The ILS and my wingman dropped me off on a decent start and Paddles was able to talk me into the wires.

Finally on deck, I was very thankful for the crew coordination that helped me get there safely. I was able to get help in quickly sorting out functioning reference points for airspeed and altitude. My wingman assisted in my descent and line up, and Paddles put the finishing touches on a flight that I would rather never repeat.

Although I had practiced standby approaches at the field, I was not expecting the lack of VSI in the HUD and the inability to use auto throttles that came with a full ADC failure. In addition, this failure reiterated the importance of referencing 10 degrees of pitch attitude with the waterline symbol coming off of the cat. If my cat shot had occurred just a couple of minutes later I would have launched without a visible horizon and with a questionable velocity vector. Not a comfortable place to be.

My next set of carrier qualification workups will definitely incorporate ADC failures in the simulator. Up to this point, I have always just selected STBY on the HUD to simulate a standby approach. Unfortunately, as mentioned above, this does not completely imitate the totality of systems lost. Practice, a knowledgeable representative and some help from paddles is essential in turning a bad night into an earned meal at midrats.

About nika