(What’s this? An update? No way!!! Really… I’ll try to be better about it for the next few months anyway)
It’s my first day back in the plane in almost a month, and things aren’t going well. After two weeks of Union work and two weeks of vacation, I’m working my first early morning in several months and as if that isn’t enough, I’m dealing with a broken airplane and nasty line of weather. Somewhere below us the rugged ridgelines of the Smokey Mountains are lurking in the cloud bases. Both the FO and I have our radars turned on trying to avoid the worst of the weather, which means we’ve lost our real time visual depiction of where the peaks are. ATC is keeping us clear of them, but I hate relying on them to do that and would much rather be able to verify their vectors.
About 20 miles away Knoxville is reporting low overcast skies, rain and gusty winds. Between our present position and the runway is a mass of orange and yellow radar returns and, if the current conditions continue, a whole lot of turbulence. On top of that it is below freezing up here and we are picking up light ice on the airframe. It’s nothing that the anti ice system can’t keep up with, but it is rapidly turning what was a quick 35 minute flight in a much more involved ordeal.
Our real issues, and the ones we left the gate in Charlotte with, are that the charger for one of our two onboard batteries is acting up and the valve that directs air from the auxiliary power unit to the aircraft’s pneumatic system is jammed closed. Maintenance “fixed” the charger problem while we were on the gate, although apparently the part they replaced is either broken as well, or not the culprit to begin with. Every large bump we hit knocks it off line for a few seconds, flashing a caution message onto our displays.
Although this is annoying, and probably has long term ramifications, I am less concerned about this issue than the lack of APU bleed air. Because the engines can’t supply all of the pneumatic systems’ needs (engine thrust, cabin pressure and wing and cowl anti ice) something has to get dropped during high demand periods like takeoff and landing. Obviously we can’t do without engine thrust, and because of the icing conditions, we can’t turn the anti ice system off. That means the only thing we can turn off is our pressurization which leads to some mild ear discomfort. We don’t have to turn off the system until we are about to put the flaps out, so as we bump along through the clouds I carefully visualize our descent path and associated speeds so I can have some sense as to when we will have to slow and put out flaps, necessitating turning of the air conditioning packs, and causing the cabin altitude (currently at a comfortable 1000 feet) to start to raise to our actual altitude.
ATC turns us towards the finals, now 10 miles away and on the other side of a nasty looking radar return. I have the FO request 10 degrees to the right from Knoxville Approach so we can slip around the weather, which they quickly grant us. The ride is still pretty rough and heavy rain lashes the three layers of glass making up the windshield. It’s warm enough now that the ice has stopped forming and is melting off in the deluge we are flying through, but the anti ice system still has to be on because the temperature and moisture outside could produce airframe ice. Realizing we are going to have to slow down sooner rather than later I give the go ahead for the FO to shut off the pressurization system.
As the engine bleed air valves close I can feel the cabin pressure rising in my ears and in my nose. I try to yawn to equalize the pressure but only one ear clears. By now the cabin has climbed from 1000 feet to about 2000 feet. Clear of the patch of weather, although still flying through heavy rain, we turn back towards the finals and are cleared down to 2700 feet. We get there about the same time the cabin pressure does. From here on in the cabin pressure will change at about the same rate our altitude does, which means I need to be very gradual in any climbs or descents.
ATC turns us toward the field and clears us for the approach. I remind myself I haven’t actually landed the plane in about a month and with the gusty winds and low visibility on the surface, I need to just settle for getting it down and worry about nice landings another time. We join up on the ILS and start down into the murk below. The rain lightens in intensity, just about the time my other ear clears. They are reporting 500 foot ceilings and as advertised, the ground comes into view just at the plane calls off 500 feet.
The plane buffets in the wind and I flip the windshield wipers on to clear the rain streaking up the glass. The runway is clearly in sight now, stretching out over the grey, rain filled landscape ahead of us. I take one more glance across the overhead panel, noting the multiple push button switches normal dark, now illuminated because of the odd configuration we’ve put the plane in due to the maintenance issues. The left wing drops slightly and the autopilot violently corrects in the other direction. I tighten my left hand on the yoke and my right hand on the thrust levers and then disconnect the autopilot. I may not be as precise as the autopilot, but I can be much smoother in this sort of weather. The plane slews slightly until I adjust the pressure on the yoke so that it flies straight towards the rapidly approaching runway.
I take a quick breath; remind myself how to land, and then grin. This one might be kind of sporting…