Tuesday, July 7, 2009

I had a question, and my Radio Shack clock had the answer!

Today started nice. Well nice enough. I woke up at 5:40AM. The hotel I was staying at is very nice. The rooms were all recently redone and are very contemporary. They have 32 inch LCD HDTVs WITH HD content, new beds with very comfy pillows...nice work area...very nice. One thing I don't like is the thermostat. It lies. I know it lies. I carry along an atomic alarm clock (from Radio Shack $10...I love it) that has a built in thermometer. I have tested the thermometer against my home A/C along with other hotel air conditioning systems. The thing is pretty accurate. This hotel thermostat is a big liar.

I set it on 65. The system cycled off as though it were 65....but it was really 72! This was after a night of cycling on and off like it was actually cooling to 65. LIAR!

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The crew was in the van at 6:20AM. We all cleared security by 6:45AM. The Captain I am flying with hasn't had an overnight in a loooooong time. The training department pilots typically only fly day trips and turns. Kinda funny. He asked me if all the hotels were this nice. It would be nice if they were...but they aren't.

We had the same plane we flew in last night. Upon powering it up the backup Radio Tuning Unit (RTU) was flickering on and off. It's not needed. We powered the plane off and on...same result. A few minutes later the Captain had the proper authorizations to MEL the RTU to be fixed in base. We ended up leaving 1 minute late.

The flight back was mostly smooth. Oh yeah...about Captains from the training department.

So most modern jets have the ability to take off at a reduced power to save engine wear and fuel. In the CRJ it's called using "Flex" power. For full power takeoffs, in the CRJ700, the FADEC samples the outside temperature and adjust the power output for takeoff power accordingly. The warmer it is outside, the less power available and vice versa.

For "Flex" power takeoffs we tell the FADEC computer to pretend it's much warmer than the real outside temperature. This new temperature isn't pulled out of thin air, we consult charts. We have takeoff performance data for every runway at every airport we visit. The charts have allowances for headwinds and tailwinds, Engine ECS (Environment Control System....how we power the air conditioning system) and APU ECS and so on. Most Captains will not take any credit for headwinds (better safe than sorry), but will take all detriment for tailwinds. The charts give the max temp allowed for various takeoff weights and situations. The charts allow the plane to meet all required performance requirements for takeoff, climb out and obstacle clearance.

With that said, most Captains I fly with use Flex power when we can. There are some situations where we aren't allowed to use Flex power such as wet/contaminated runways, high winds or with certain MEL's. Most Captains don't use the maximum allowable Flex temperature. Why? Well it's not very comfortable. It's all in our heads...but seeing the end of the runway rapidly approach waiting for VR when you are normally airborne just feels odd. I've had some Captains put in the highest allowable Flex reference temperature on takeoff and then had a power INCREASE when, during climb out, I select climb power. Most of the time when going from takeoff power to climb power, the power is decreased.

Yesterday on my leg out the Captain put in 48 degrees for a Flex reference temperature! Normally I use 42 for departing our base. No matter how heavy we are, 42 degrees always works for a Flex temp when leaving from our base.  I checked the charts...48 degrees was legit for the runway, weight and conditions. When I selected takeoff power....it just felt sluggish. I think we used 7000 feet to reach VR. Crazy. Climbing out through 2300 feet  and about 220 knots, I selected climb power....no change in the N1 setting. Eh...

This morning we pulled into the gate at 8:56AM...a few minutes early. I made a quick call to Crew Scheduling...released! I had the rest of the day off. Tomorrow I was hoping to get reserve at home. Too bad for me the morning airport standby shift isn't covered.....guess who got it? Yeah. Not very happy about it. I'm not good for an overnight, so I am of limited use to scheduling. Oh well. I have to update my charts anyway.

I took this photo months ago during an overnight. Pretty neat.

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  1. Regarding the thermostat, this flyertalk thread may be of use to you...


  2. I love this line "We powered the plane off and on…same result" , doesn't matter if its a $200 phone, $500 computer or $30 miliion CRJ, a reboot is always a good place to start!! Keep up the good work mate, I always enjoy reading your blog.

  3. Your blog entries always gives me greater insight and I always look forward to reading them. Thanks for deciding to keep posting.

    And thanks for answering our questions.


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