To: (Separate email addresses with commas)
From: (Your email address)
Message: (Optional)



How One GPS Source Crashed A Pilot's Navigation Equipment In IMC


Technology in the cockpit has made flying cross-country and IFR easier, and much safer, than ever before. That is, unless something goes wrong.

With GPS, ADS-B, glass-panel avionics, tablets and smartphones, there's almost infinitely more technology in your cockpit than what it took to land on the moon.

But when things go bad, they can go really bad. With the complexities of panel-mounted and portable systems, diagnosing navigation problems in the air is can be a real hurdle. Add in data streaming products, and it can be hard to figure out what data you can rely on, as the pilot found out in the flight below.

An Easy Flight, Or So It Seemed

The pilot, flying a Beechcraft V35, departed VFR, and planned to pick up his IFR clearance in the air.

His aircraft was outfitted with an Aspen 1500 system, Garmin GTN 650 Nav/Comm unit, and a Garmin GTN 210 Flight Stream unit.

In addition, the pilot had a yoke-mounted iPad with Foreflight, connected to the panel with Flight Stream.

Mot the barber

Departure, And Looming Weather

The departure was at dusk, and there were squalls in the area.

On climb out, the pilot called ATC at about 2,000 feet and picked up his IFR clearance. ATC cleared the pilot for a direct turn on course, and at that point, the problems started.

The pilot immediately noticed a GPS error on the flight panel. GPS signal was briefly lost, and the pilot continued in heading mode. After about 30 seconds, the pilot reported that GPS signal was restored, and continued on course, climbing for 5,000 feet. He was still in VMC, but there was weather ahead.

The pilot asked ATC if there were any reported GPS outages, and ATC replied that there were no reports. At that point, the pilot contemplated remaining VFR or turning back, but decided to continue the flight IFR.

Clouds, Rain, and Turbulence

On his way to 8,000 feet in the weather, things really went south.

The pilot experienced another GPS failure, but this time, things started adding up. He also had an ADS-B failure, and had multiple failure messages on his GTN nav/comm system.

Knowing that he had his iPad up and running, he didn't panic, and he decided he could continue, at least for the time being, in heading mode, along with nav information from his iPad.

Unfortunately, because his iPad was connected to his panel through Flight Stream, it was also receiving bad data, but he didn't initially know it. There were no error messages on his iPad, and it wasn't until he saw a 90 degree course error on his screen, that he realize that things were bad on Foreflight as well.


Where's The Good Data?

At that point, the pilot lost confidence in his panel and iPad, and reverted to backup instruments, including his compass. It was an experience he described as "no fun". That's probably putting it lightly.

In the darkness, rain, and turbulence, he started troubleshooting the problem. Did he have a reception problem, or a cable connection problem? It was a question he didn't have an immediate answer to. And in IMC, he wasn't a good situation, to say the least.

As he stepped through the possibilities, he realized that the panel was feeding bad data into his iPad. After disconnecting the two, he got his iPad back, and his situation started to improve.

Know Your Avionics

The flight resulted in a safe landing, but the situation could have gone worse too.

It's easy to say at the first GPS signal loss, the pilot should have returned to the airport or stayed VFR. But with a momentary GPS signal loss for only a few seconds, it could have been just about anything.

Unfortunately the problems got worse in the clouds. And after some hand wringing, and probably some swearing under his breath, the pilot was able to figure out that his panel was feeding bad data into a perfectly good tool: his iPad.

After understanding the problem and disconnecting the two, he was able to get back to a semi-normal flight. Had he not been able to determine the problem in flight, it would have a been a much more challenging remainder of the flight.

Colin Cutler

Colin is a Boldmethod co-founder, pilot and graphic artist. He's been a flight instructor at the University of North Dakota, an airline pilot on the CRJ-200, and has directed development of numerous commercial and military training systems. You can reach him at

Images Courtesy:

Recommended Stories

Latest Stories

    Load More
    Share on Facebook Share on Twitter Share via Email