I thought I would lighten the discourse for a bit and speak of something from my 'past' as an airline guy in Operations and consultant for an aviation company out of Long Island, NY.
I'm waiting for a flight. The arrival gate shows C6, why did it change?
In most cases airplanes flying on instrument rules (all commercial airlines) have a set route. These routes are like highways in the sky with attendant rules to follow.
If a flight is longer than about an hour, there are probably several if not more 'checkpoints,' known waypoints to report position, outside air temperature (a topic for another blog one day) and estimated times of arrival. Normally a pilot will not deviate from this route unless given permission by the FAA controllers AND the airline dispatchers.
Why is that? Flights are planned based on multiple factors including weather enroute and closest distance. In the past, and I am speaking from experience here but the rules might have changed, any deviation of more than 100 nautical miles required approval from the dispatcher whether in Flight Control, Operations Command Center or the System Operations Center, dependant on the name given by the individual airline.
Why is that? Obviously the crew and 'company' want to avoid dangerous weather. If one looks at a weather map of the U.S. one will usually find several 'high pressure' and 'low pressure' areas. Flights are planned to take advantage of the winds in those pressure areas. A Low over Ohio for example turns in a counter clockwise motion. If an airplane is flying from NYC to SLC then the dispatcher would try to route the aircraft to the north to take advantage of the winds blowing to the West.
Even more so, a deviation could result in a further delay due to increased head winds or other factors. Hence approval from the dispatchers at OCC or SOC.
Okay, so you fly from Boston to Salt Lake. A 'normal' flight is about 4 hours or so. But with the tail winds riding over the 'top' of the Low, the aircraft might arrive early, even 45 minutes or more. Why am I early and yet have to sit for 30 minutes waiting for a gate? Why not just move the airplane to another gate?
In years of working Delta Ground (Control) I faced this many, many times. Pilots and passengers hate to wait but there are a bunch of considerations here.
1. Is there another gate which will accomodate my type of aircraft? A Boeing 767 will not 'fit' in a 737 gate although the reverse is often true. However using another gate invariably causes the same problem for the other aircraft waiting.
2. When a gate is 'changed' it causes a lot of problems. Passengers go to a gate expecting to depart out of it and miss gate changes. Cargo and bags need to be moved to the new gate. Often gates are set up in advance for convenience of connecting passengers. Changing gates disrupts this.
3. Sometimes it is as simple as having mechanics and parts available to work on scheduled maintainence.
4. A little known fact except to the 'world traveler' and now you can be just that. Pilots and flight attendants do not always follow the aircraft nor each other. Because of schedules, FAA rules on hours worked and other disruptions along with the aircraft 'in' does not always make up the aircraft 'out' consideration is made to insure that arriving crews are able to connect to their new flights outbound to allow for cockpit checks by the flight crew, cabin and safety checks by the flight attendants.
Whew, lots of info here but I will adddress other issues in another blog. Please send comments and suggestions along with anything that you really wanted to know about airlines (within my expertise, of course) to Bob@UrbanUtah.com
Hope you had fun and learned something!
