Flight Log: Shobdon Interruptus

Preflight

Sometimes things just don’t work out well. This was one of those flights: a friend and I planned a coffee trip to Shobdon near the Welsh border on a sunny Sunday (it’s in the name, isn’t it?), and I had CY booked again for a 4 hour slot, but this day was supposed to prove how hard it is to fly when you have a major distraction during the entire flight.

Departure

Everything was looking good at the start, the aircraft was checked and recently refueled, I called Shobdon for airfield information and booked a PPR slot, and the weather turned out to be fine all day.

We started the engine and taxied to runway 18 for take-off. Wellesbourne was very busy that day, but we quickly found a gap to get off the deck.

Soon after we became airborne I noticed a very loud hissing noise on my headset, which made it really hard to hear any radio communication. I asked my friend Mike if he hears any noise on his headset and he said he doesn’t hear anything. That made me very suspicious and I thought it was something about my headset connection or similar and I could have a look once I leveled off, away from the busy circuit and after the climb, which is certainly not a good time to fiddle with your communication devices while flying.

Cruise

I informed Wellesbourne of our departure to the west, set course towards Worcester using the HAT mnemonic, performed a FREDA check and then started my investigation in order to nail down what caused the noise in my headset.

I had my little voice recorder attached to the audio output socket of the plane, so that was my first suspect. We’ve passed Stratford upon Avon and I decided it was safe to quickly disconnect my splitter cable and audio recorder and reconnect my headset directly. But it didn’t help.

I turned down the volume on my headset. Obviously that got rid of the noise, but it also got rid of everything else.

I turned down the volume of the radio to the same effect.

I tried fiddling around with what I hoped was the squelch knob of the radio. No improvement.

I turned the radio off and on again. The noise persisted. This indicated that it was not a radio issue, but rather something with the intercom. It sounded like a microphone that was installed outside the aircraft and picked up the wind.

I couldn’t figure it out, so I decided to abort this mission and return to Wellesbourne. I felt sorry about Mike, and so I offered him a sightseeing trip around Worcester instead, which he was happy to accept. We already made quite some progress towards the west and Worcester wasn’t far away, so I just had to swing around the back of the city and fly back.

Arrival

The arrival was when I really noticed how much of a distraction this whole thing was. We arrived overhead and descended on the dead side. Once I turned north onto the downwind leg the stress level increased with several aircraft in the circuit and a radio that was hard to understand. I turned the volume all the way up to hear what the tower was saying.

IMG_0022.PNG
I really screwed up my downwind leg!

I did the pre-landing checks and hastily aligned the DI with the compass, but I soon drifted off to the right, thereby shortening my base leg. Once on base I noticed that I almost immediately had to turn final, and therefore I was a little high on the approach. In addition my friend Bartosz suddenly appeared in front of us with a glide approach.

I decided to both get lower and get some distance to Bartosz by swerving left and right, which proved very successful and I quickly intercepted the regular glide path, but by this time there was not much altitude left shortly after we were already landing. Bartosz had gone around, so the runway was all mine. Due to the late establishment on final the landing was not my best as the ground effect caught me again, but overall it was safe and event-free from there on. For some reason the hissing noise has disappeared now.

Conclusion

Although I felt sorry for Mike that I couldn’t fly him all the way to Shobdon that day, this was a very interesting flight for me. It tested my abilities with unexpected situations, and I’m glad I decided to return home once I knew I could’t fix the problem while airborne.

Back home I went for the omniscient wisdom of the internet in hopes of finding an explanation for the intercom noise. One forum thread that I was reading mentioned a similar phenomenon and traced it back to a slight gap between the door and the airframe. This would explain the wind noise which could’ve been picked up by our microphones.

Since I tried to adjust the squelch with no effect I assume that this was the cause of the noise, and next time I guess I have to make sure the door is properly closed and latched.

Flight Time: 0:50h
Total Flight Time: 5:20h

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s