Ask The Captain

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Let me state that I have no word from United about our CEO but he is in my thoughts and prayers.

737-900 Weight and Balance

On my layovers I pre-write business cards to my customers thanking them for their business. Before departure I get the manifest from the agent then during cruise I add the customer’s name to the card. I recently received a response from Mrs. XXX, concerned that an aircraft she was on might go into a tailspin and was deeply concerned. Exchanging a couple emails I found that she was on a 737-900 and was a bit confused when the captain was explaining the weight and balance issues with this aircraft and that everyone had to wait till 40 bags were removed before deplaning. Say that the aircraft might tip on its tail gave her immediate concerns of what might happen in flight.

This is the reason I engage my customers. Flying is not a mystery but can be confusing. I feel it is easier to keep the customers we have than to find new ones. By taking the time to answer Mrs. XXX’s concerns she remains a loyal customer. Additionally she gets that I love flying, (second to my wife), and it is a very safe mode of transportation.

Before I get into the meat of this topic I have been asked through the years how often do pilots use the autopilot? Again weight and balance comes into the picture. During cruise for example the aircraft has to be balanced within certain parameters. Any fuel burned or customer movement the aircraft has to be trimmed for level flight. In my Navy days flying the P-3 Orion over the Atlantic Ocean the enlisted personnel always challenged the new pilots flying ability. The aircraft commander would tell the young Ensign to turn off the autopilot and hand fly to get use to the controls and practice trimming the aircraft. On his signal all the crewmembers, roughly 12, would walk to the rear of the aircraft. The aircraft would begin a climb as the nose pitched up. The Ensign would re-trim the aircraft again for level flight. Again the signal would be given and the crew walked forward putting the aircraft into a descent. This procedure continued till the Ensign could hear the laughter in the back and know that he was being set up. It’s just a little humor to pass the time while flying to the location to start our mission of tracking Russian submarines. As for any airliner, movement in the cabin requires a re-trimming of the aircraft. The autopilot senses it way before the pilot possibly can and this is what gives you a smoother ride. Most pilots will hand fly the aircraft to cruise altitude then turn on the autopilot.

The 737-900 came to the industry with a weight and balance issue after landing. It doesn’t happen often, maybe once every two weeks, but bags have to be deplaned before the jet bridge is brought to the aircraft. If too many customers get off the aircraft before the bags are removed the aircraft may tip on its tail. I have not heard of it actually happening but if you were involved in a tip or near tip let me know.

The 737-900’s center of gravity is calculated prior to arrival so the station is aware if there is a weight and balance issue. The captain is notified and makes the appropriate announcement. The jet bridge stands off from the aircraft for two reasons. First so that the flight attendants do not open the door and people begin getting off and secondly each jet bridge has a leveling system which has to be adjusted as the bags are being removed.

There is a fix coming. An IAH mechanic designed a telescopic stanchion that will be fixed to the belly of the aircraft. Upon blocking in at the gate the ramp personnel will extend the stanchion so it will support the weight of the tail and deplaning can begin immediately and not interfere with your travel plans. The design is complete but United is waiting for approval from the FAA which takes time.

This is my second post with “Ask The Captain” and I welcome your questions.

Capt. Denny

Comments

  1. YULtide says

    Interesting post! I fly A320’s pretty often and notice that there is an odd sound like something is being winched during taxiing. I’ve always been curious what this sound is, and would appreciate your insights.

    Thanks in advance!

  2. robin says

    On many planes especially smaller ones there is sawing sound after the aircraft lands which I assume is something to do with bringing the flags back to position. Can you explain it if you know what it is ?

  3. Ulev says

    Having recently flown the new AA 737-800 series I have given up all hope of choosing an exit row seat… The new seats are so narrow with the immovable tray column that my first thought was ‘ made this way so that seats could be used as a ladder to climb out the exit if the plane was on its side”
    Time for me to move on, as my ‘favorite Mad Dogs’ are being retired and barely sufficient seating option have taken their place….

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