What is a relief tube?

When people ask me what I think of the King Air that I used to fly, what was my favorite thing about the airplane, I have an immediate and firm answer.
It has a pilot’s relief tube.
I was taking customers to KMLI in a Cessna 340. This was back in the 90s so we are talking steam gauges and Jeppesen binders. Cell phones were still a novelty. I had a co-pilot with me who’s day job was FO for a major airline. Great guy. As I’m getting the plane ready, making sure snacks are on board, herding the cats which our customers generally were, I made a quick mental run through of all the items that I’d need to do before I left. This is something they don’t teach you in pilot training.
Track a VOR, yep.
Power off stalls? Right there on the syllabus.
Did you arrange the rental car at the destination? Uh yeah.
What about the customer who only drinks that one brand of bourbon. Did you get some mini bottles of that? Of course
AND remember to bring them with you to the airport? Um..
And two carafes of coffee, right? Because that one guy last time wouldn’t drink caffeinated coffee.
Everything was ready to go, except I really should go pee before we hop in the airplane….
Nah, I’ll just go when we get to our fuel stop in KY. Loaded as heavy as we were, and with the head winds we were expecting, we had to stop for fuel and Bowling Green, KY looked about right and wasn’t so far away that I couldn’t make it.
So I closed the air stair door, sidled up front, and off we went.
Despite this being back in the stone age, we did have a King GPS in the plane, state of the art with its green 2″ monochrome screen. It was really neat to be able to twist knobs and push buttons and calculate the actual winds aloft and our expected arrival time. Unfortunately I must not be very adept at using it, because instead of the 20 knot quartering headwind that was forecast, this stupid thing keeps saying I’ve got 45 knots on the nose. That can’t…be..right…
Ugh. This is going to be a long trip.
As we toodle along at our greatly diminished ground speed, my lack of hitting the facility before we left is becoming a problem. I try to think happy thoughts, talk to my co-pilot to keep my mind off of things, and generally be a professional and pretend there isn’t a problem. Instead I’m watching everyone guzzle coffee and I’m getting unwelcome mental images of Niagara Falls.
I’m furiously calculating and recalculating the winds aloft, trying to figure out a way to make our ground speed better. Maybe a bit higher? A bit lower? But hemmed in between the fuel range with NBAA reserves, the steady headwinds, and our planned fuel stop, I don’t have a lot of choices.
As we get closer to our fuel stop, I progress from uncomfortable annoyance to horrible pressure to I’m going to need a doctor if this goes on much longer. Finally we begin our descent into KBWG. I’d mentioned to my co-pilot, during our cruise portion, that I really needed to go to the bathroom.  He acknowledged and dismissed this bit of information with an easy indifference. Not my bladder, not my problem. But as we started down, I told him I may need his help on landing.
“Why?”
“Because the pain is so bad, I’m not sure I can use the rudder pedals.”
Now he looked invested in the conversation.
At this point, I know what you are saying to yourself. “Self, what kind of idiot gets himself into a situation like this? Why didn’t he just stop short and go to the bathroom?”
First, all options were considered and discarded. If we stopped short, with these headwinds, that would turn this flight into a two fuel stop trip instead of one. Something I’d have to explain to the boss, and to the customers. It would add time that we didn’t have, and cost that wasn’t needed for my personal comfort.
Second, as the guy who supposedly knows what he is doing, being the one who didn’t go to the bathroom before we left is not something I wanted to admit. I’m not saying pilots are prideful, but…
Third, we’ll be there shortly. I can make it. (repeat quietly to yourself over and over)
I flex out a few tentative rudder pushes and I can make do. We’ll be on the ground soon so we’re good.
“N12345, turn left 20 degrees, this will be vectors for the localizer approach. Glide slope is out of service. “
What? No ILS? The minimum descent altitude (MDA) for the localizer will get us in, but just barely. Great.
We cruise along on vectors, and then after intercepting the localizer, we wait for clearance to actually start the approach and descend.
“Uh approach, N12345, can we start our descent?”
“Negative 345, traffic below, will be a few miles.”
We are getting closer and closer to the airport. With turbocharged piston engines, I can’t just yank the throttles and push the nose over. I have to worry about shock cooling. Finally when we are about to request we turn around and try again we blessedly get the approach clearance. I pull power as much as I can and nose over to get to MDA, tracking the localizer inbound.
Just as we get to MDA, we pop out of the clouds and there is KBWG bright and clear and beautiful.
And almost directly below us.
My copilot looks at me with pity in his eyes and says, “Sorry, no way you can make it from here. We’ll have to go around.”
My calm and professional response?
“Screw that.”
Using my recently tested skills of rudder mashing, I put in a heap of right rudder and drop the left wing. The 340 slips beautifully. If you haven’t tried it, have a go. I’m looking at the runway out of the side window, holding my slip to get down to a landing position. I glance over, now up in our slip, to my co-pilot. He’s as white as a sheet and not saying anything. The customers are still chatting away amiably in the back, oblivious. A slip entry and exit are gentle and everything is shaping up nicely, even though this is the longest and steepest slip I’ve ever done. But all is well, why is he so upset? I query him quickly and he just shakes his head. No time to figure it out now.
I pop out of the slip, drop full flaps, and touch down without a problem, making  the last turn off with little braking. Before we are off the taxi way I’m already out of my seat belt, pushing through the customers, and at the door ready to drop it the moment the co-pilot stops at the ramp.
Several minutes later, my co-pilot takes up station at a urinal beside me in the bathroom. I look over and ask him, “Hey, why’d you look so scared on the way in?
“You can’t slip a 340.”
“Yes you can, I just did. You can slip a Boeing, why wouldn’t you be able to slip a 340?”
“It is a prohibited maneuver. It is in the POH.”
“What?! I’ve never seen that. Why is it prohibited. It slips just fine.”
“It unports the fuel pickups. The engines will quit.”
After several seconds of bladder relieving thought, I replied. “We were already too high, I didn’t need engines anyway.” What else can you say at that point, we were down and safe.
After completing our trip and seeing our customers safely delivered to their destination, we pulled out the POH and did a thorough review of any and all limitations. My intrepid co-pilot, unfortunately, spent his time bouncing between airplanes and had mistaken the 400 series Cessna no slips limitation for an all encompassing twin Cessna limitation. 340s are indeed able to slip freely.
Today my daughter, whenever I mention the possibility of buying an airplane, only asks one question.
“Does it have a potty?”
That’s my girl!

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