Wednesday, September 12, 2018

Eagle eye challenge revealed

It's been over a month since I posted the Eagle Eye Challenge. Many of you responded, but for some unknown reason I didn't get any of your comments until the first week of September. During that time, I supposed that nobody was really all that interested, which is believable considering how infrequently I post updates nowadays. But now that that's been resolved, it's time to show you what you were looking for!

I opened above with the original shot of the Hawaiian A330. This was a shot of opportunity, and as such the photo had to be taken through the tower window shade, which both reduces the clarity and distorts the color. Imagine holding the dirty lens from a cheap pair of sunglasses in front of your camera lens to take a photo - that's the effect that I get when I have to shoot through the shades. The solution photo, taken a few moments later, was also shot through the shades, but I've tried to clean it up a little for you:

What's missing from this picture?
From this angle, it's clear that the Hawaiian Airbus is missing its left winglet. Apparently this aircraft had been involved in a ground incident with an American aircraft and the winglet was damaged in the process. At least one of you alluded to this in your comments. I wasn't there at the time, so I can't say of my own knowledge. In any case, Hawaiian operated the aircraft this way for a couple of weeks. I wonder how the flight crew explained it to the passengers?

This was the opening photo of the Eagle Eye post. This one attracted a wider range of responses, which I'll address shortly. But first, here's a highlighted version of this photo:

Now, a tighter shot that has less clutter:

And now, that shot with big arrows:

By now, it should be clear that what's happening here is something that, as a controller, you normally don't want to see: Two aircraft on the same runway, at the same time. What is taking place here is that an aircraft is holding in position part-way down the runway for an intersection departure while another aircraft is holding in position behind it. On the left side of the photo is a B747 holding in position on Ry25R; on the right side of the photo is a Gulfstream G-IV (I think) also in position on Ry25R at an intersection downfield. 

Here's a shot of the airport diagram with the intersections involved marked. I've deliberately printed it upside down (north bottom) because this is the same orientation as the above photos and is more representative of how the south side of the airport appears from the control tower: 

This edition of the chart will be obsolete by the time this blog post gets published. Not for navigation!

There are a number of limitations on this sort of operation at LAX, which is what makes it noteworthy. Without getting too geeky, I'll try to describe them:
  • The G-IV is at Taxiway G, which is only allowed to be used for an intersection departure if the runway is not available for arrivals, there is nobody cleared to land on it, AND the Local Assist position is staffed.
  • A jet aircraft is not normally allowed to depart from an intersection in front of another aircraft holding in position due to jet blast concerns. However, Taxiway G is far enough down the runway that it is allowed in this case.
  • The tower controller must be able to see both intersections clearly and must tell each aircraft about the other.
  • If you look closely, you can see that the B747 is also an intersection departure from Taxiway F. If the B747 was at the full length of the runway and the G-IV was at F, we would not be able to do this. However, if the B747 was at the full length of the runway and there was a propeller aircraft at F, the operation would be allowed. We do occasionally run that operation with a Cessna Caravan, Beech 1900, or E120 Brasilia (and others).
  • While we can perform this operation during the day, at night it would not be allowed because we are not able to put aircraft in position at an intersection after sunset.

Now I'll address a few of the other comments:

  • Several comments mentioned United aircraft at Terminal 7. The widebody at Gate 72 is actually a B787 (the wingtips give it away); B777s have also been known to utilize this gate. In order for the aircraft to fit, it has to be parked at that angle so as not to block the rest of the alley. This results in the loss of a gate; when only narrowbody aircraft are involved, there are two gates in that space: 72A & 72B. 
  • On the west side of Terminal 7 can be seen a United B757-300 at Gate 71B. We get B757-300s in both United and Delta colors, but they are not as ubiquitous as the shorter B757-200, which both airlines (and others) also operate at LAX. As was mentioned in the comments, the B753 also has to be parked at an angle to clear the alley. As a side note, each gate at LAX has a list of aircraft that can be accommodated at that gate. The tower controllers are aware of some of these, mainly the ones that involve restrictions on adjacent gates. This can occasionally be the cause for an aircraft being unable to go to the gate after landing: While the assigned gate might be open, the gate next door has a conflicting aircraft that will have to clear first.
  • There were a couple of comments about the cargo ramp. This photo was taken on a Monday, which is FedEx's layover day. Not many FedEx flights occur on Sundays, so their ramp tends to be full on Mondays. All of those aircraft will leave later in the day and evening. We don't normally get Prime Air at LAX, but we do have a couple of other operators with similar paint schemes.
  • Virgin America and Hawaiian both used to operate out of terminals on the north side of the airport. They were displaced to the south side when Delta moved all of its operations to the north side. Virgin America is now part of Alaska, and both of them are now at Terminal 6, which they share with Air Canada. Hawaiian is now at Terminal 5, which also has Allegiant, Frontier, Jet Blue, Spirit, and some American flights. Despite being parked on the south side, Virgin America/Alaska and Hawaiian will still sometimes be sent to the north side for departure, depending upon what their route of flight will be after takeoff. The same applies to the other carriers that park on the south side, while operators on the north side will sometimes be sent to the south side for departure for the same reason.
As I noted earlier, the airport diagram will not be current by the time this blog post gets published. Do not use it for navigation. You can get a current edition for free from the LAX airport page on AirNav:

1 comment:

  1. As for your question regarding what to tell the pax about the missing winglet...I'd say nothing unless asked, then tell the truth. I say this as a retired Captain. I'll bet you five dollars that no one noticed anyway. A missing winglet is all covered in the CDL (configuration deviation list). The Dispatcher and Captain have all the info they need to add additional fuel, etc.

    Then again, some aviation geek will sit in just the right seat to see exactly where the winglet should be :-)