You Just Lost Your Only Attitude Indicator In IMC...Now What?

Trapped above the cloudy IFR conditions below, this pilot was left with a real-life partial panel situation as his attitude indicator began to fail.

A Lucky Story

Pulled from a NASA ASRS report during early 2016, this pilot recounts his experience while flying a round-dial PA-32 Cherokee Six on an IFR cross-country...

I was en-route when the attitude indicator started showing a false reading of 10-15 degrees to the left. I informed Center of the issue, and at that point we were {given] a block altitude 7,000-9,000 to stay out of the clouds. With the AI out, the autopilot would not hold the wings level. Along the route we checked surrounding airports to see which had the best landing conditions. All the airports en-route had low ceilings with poor visibility.

Boldmethod

The destination was the best choice with a ceiling of 1,700 feet. Since this is my home base, I was very familiar with this airport. When we were handed off to approach control, I told them we had an issue and they said they were aware of the problem, and asked if the DG was working. I replied yes. We tried shooting the ILS once with no luck. I was able to keep the wings level but could not stay on the ILS path.

For the second approach, they vectored me out farther north to try and set up a stable approach for the ILS. During the approach, I lost control of the plane and struggled to keep the wings level. Losing and gaining altitude, the wings were pitched over and in general I struggled to keep the plane upright. ATC called for me to go missed and climb to 5,000 feet, but I was fighting to control the plane and did not respond back immediately. I only regained control of the plane once I broke out of IMC at or around 2,500 feet.

At that time I called tower and told them that I was wings level, and had the plane under control. I let them know I was now VFR with the field in sight. All of this took maybe 40 seconds from the time ATC last called. At that point, the tower asked if I wanted to cancel IFR... I'm not sure if I handled this issue the best, but I am still here to fill this [form] out and I'm not in a coffin. I do know that once the plane is fixed I will be working on partial panel flying with my instructor.

No Backup Installed

It's no secret that this pilot was extremely lucky. After two attempts at flying an ILS, it became clear that partial-panel flying skills weren't adequate for the situation at hand. Like most light piston aircraft with analog instruments, this Piper PA-32 Cherokee Six did not have a backup attitude indicator.

If the clouds had been any lower, this pilot may not have been able to recover, and the story could've ended with an NTSB report rather than a NASA ASRS report. When's the last time you flew partial panel with a failed attitude indicator?

How To Fly Partial Panel In This Situation

If you find yourself with a gyroscopic instrument failure, you need to identify the extent of the failure. Some aircraft have vacuum powered attitude indicators and electrical heading indicators. In others, both the attitude and heading indicators are vacuum powered. If they're both vacuum powered, your vacuum system could have failed - and the heading indicator is also unreliable. Don't trust the heading indicator until you've verified it's fine. It may take time to fail as it spins down.

This pilot was flying in VMC conditions above the clouds before initiating his approach. Don't fly into the clouds before you need to. This is the perfect time to take a step back and analyze all of your instrumentation. The report doesn't note whether the heading indictor also failed - so we don't know if the instrument was fine, or if the pilot didn't recognize it's failure.

Once you've identified a failed instrument, you should remove it from your scan. Cover the failed attitude indictor with a piece of paper if you can. Your natural tendency will be to look back at the instrument for attitude information, and you could quickly end up confused.

Your scan pattern will feel a bit disorganized - this is where practice really pays off. And, it's easy to over focus on a single instrument - keep your eyes moving along your pattern. Otherwise, you'll miss attitude changes. With the attitude indicator out, you'll need to rely on your other instruments for pitch and bank information. So - do you remember what options you have left?

Pitch Instruments:

Airspeed Indicator
Vertical Speed Indicator
Altimeter

Bank Instruments:

Heading Indicator
Turn Coordinator
Magnetic Compass

Fly your standard power settings on approach. A failed instrument doesn't affect your aircraft's performance. Know the power setting for your level flight approach speed, as well as your ILS final approach descent. As you fly the partial panel approach, keep your configuration and power changes standard. It makes the aircraft easier and more familiar to control - and you'll end up very close to your standard, expected performance.

There Are Backups Available

While you need to be ready to fly without any attitude information, there are a few backup systems you should consider carrying with you. Here are a few options:

1) Stratus: Couple a mobile Stratus device to your tablet's ForeFlight app. Every Stratus has an internal AHRS unit (attitude/heading reference system), which provides attitude and heading information based on the gyros it comes installed with. Backup attitude information is displayed right on the screen of ForeFlight.

Swayne Martin

2) Downloadable Apps: There are numerous iPhone and iPad apps that you can download to utilize the accelerometers inside your mobile device. These aren't completely reliable, but they could serve as life-saving backups in case you're left with no options.

3) Portable EFIS: Some avionics manufacturers produce a "pocket EFIS." Like the Stratus, these small units contain AHRS systems that can be great backup resources.

If you choose to use one of these backup systems, make sure you practice using it. Even setting up a backup system while partial panel in IMC can be disorientating. So, make sure you practice the whole process - from setup to final approach - under the hood.

Practice, Prepare, Scan

With an instrument rating on your certificate, it's easy to forget about the emergencies you flew during training. Add in some time since your checkride, and you could be in for a ride after a system failure. So take the time to practice - either with a safety pilot or a CFII. That way, you'll be in familiar territory if you lose an instrument.

Have you experienced a partial panel situation? Tell us about it in the comments below.