# UA 832 Cancun to Dulles, Saturday, April 23

Midway through this flight, somewhere over FL or GA, I was astonished to see a southbound jet whiz by us about 1000 ft below and 1000 ft to my right. I asked the pilot on the transporter at Dulles how close we had come and he said, “No problem, it was 1000 ft.”

Seems like we could’ve made it less exciting by inserting a few miles laterally. I travel a lot and it was the closest I have ever seen two planes at cruising altitudes.

Anyone else notice this?

Wouldn’t this constitute a near miss?

1,000 feet vertical separation is standard. With vertical separation established lateral separation can be 0.

We pass each other all the time.

Ever drop 1000 feet due to turbulence?

No and anytime there is question as to turbulence or mountain wave reducing our ability to maintain altitude within requirements we notify ATC, and/or get a larger block.

Thank you for taking the time to educate me (us.)

More info can be found by searching- Reduced Vertical Separation Minimum (RVSM). FL 290-410 have stricter standards that allow for closer separation between altitudes (And some really cool views too!).

If by drop you mean an instant loss of altitude, nobody has and lived; sensational ‘press’ reports notwithstanding.

A one-second 1000ft drop is a 60,000fpm rate of descent, the plane would be in small pieces . In two seconds it’s 30,000fpm; same result. You can do the math.

That “huge drop” folks feel on an airliner is probably a 20 foot, very abrupt movement. It’s rare to see a 100 ft. displacement in turbulence.

Yes, I had plenty in school. What’s a mathematically meaningful time to drop 1000 ft in an unusual period of turbulence? I can free-fall that in 6 seconds. Let’s double it to 12 seconds as I don’t have wings opposing the fall. You’re cruising at 550 mph and you have a plane coming at you at equal speed 4 miles out. How much time do you have to avoid a collision? Can you do that math? I can.

Why risk it when there’s so much space? 1000 ft verticle? Fine, what’s the problem with a requirement for a few miles lateral?

Crowded skies!

“The goal of RVSM is to reduce the vertical separation above flight level (FL) 290 from the current 2000-ft minimum to 1000-ft minimum. This will allow aircraft to safely fly more optimum profiles, gain fuel savings and increase airspace capacity.”

If those who sit in the pointy end of the aircraft aren’t worried about the new 1K foot separation, why are you?

Probably because they’re more used to that kind of miss in a crowded sky. As a passenger lazily looking out the window it was startling, that’s all. I’m fine with the RVSM. I just thought it would be prudent to get more lateral separation as a safety buffer. As a past skydiver I’m not risk-averse but I’m used to trying to minimize it.

What he’s trying to say is that contrary to popular myth airplanes don’t encounter turbulence of a nature that will drop you 1000 feet in a second.
If there was such a turbulence, Pilots would inform ATC that they can not hold their current altitude do to Turbulence and or Mountain waves. If that was the case ATC would provide adequate separation.
I have been flying for 15 years now and have only once not been able to hold my Altitude with in 100 feet.
BUT that was in a cessna 210 and I was vectored into a lvl 5 thunderstorm (I had no on board radar) by Memphis Center.

Also MOST of the nasty up/down drafts are encountered in thunderstorms, something we try an avoid. If you do find yourself in a thunderstorm chances are you’re the only idiot that chose to fly that route and there is no one to hit

Are most of you RVSM kids flying SLOP?

Wow- 4 years of flying Turbojet aircraft and that’s the first I’ve heard of that one.

I do know from exp. that when flying in non-radar in South America that the north bound routes tend to be different then the south bound, and this my be the reason why?

There’s a difference between a ‘drop’, implying a flat downward trajectory, and a dive which is a nose-down attitude. It is theoretically possible that another plane 1000ft above could dive into yours in a couple of seconds but that would require so many factors to coincide that it’s an extremely unlikely possibility. Then there’s Murphy’s Law .

China Airlines flight 006 (747SP) experienced a loss of control and reportedly descended 10,000ft in 20 seconds. But it was in a dive (and bank) and not related to turbulence.

Yes, when following behind big stuff at the same or next lower 2 altitudes or it makes sense (w/ ATC permission or notification) Some times atc gets worried when you slide to the outside edge of the airway.

The other day I was just ahead of a life guard that wanted to go .80, but I was stretching my legs and slowed down to .74 and couldn’t accept lower for fuel range. I offered to fly a 10nm offset and let the life guard pass so he didn’t have to slow down or both of us get turns. It worked nicely.

tclassick- You should feel completely safe in RVSM airspace, because, you are. The aircraft and crew are held to extremely close expectations and any deviations will result in immediate action from controllers. In order to even fly RVSM the a/c must have at least 2 functioning altimeters, an autopilot (and use it) and may not deviate any more than 300 feet from assigned altitude. That is a MAXIMUM allowable deviation. The autopilot is expected to keep it less than 65 feet. Anyone that can’t comply will be asked to leave “the sandbox” and fly at a different altitude. There are a few more rules as well, but these are the basics… I’m sure the others will chime in with anything I missed.

If you have never seen another flight pass as close, it’s probably because GPS keeps most a/c on airway centerline fairly well and therefore not visible out the side windows except at intersections.

As for the SLOP thing, I think that’s mostly when you’re out of a radar controlled environment (as was mentioned a la Mid-Atlantic)

Do you happen to remember the tail number?