51 votes
Accepted

What does ATC do during "slow" times?

Admin stuff, emails, chat with a colleague if you are not alone on shift, read up on (ever changing) procedures, eat, read a book, make sure the coffee machine works, meditate, watch TV. Anything goes,...
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48 votes
Accepted

How do hot air balloon pilots avoid collisions?

I grew up in a family hot air ballooning business, and while I haven't been involved in a few years, I can answer your question in two words: They don't! Taking Off As far as collisions go, the other ...
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  • 656
43 votes

How do airplanes maintain separation over large bodies of water?

To expand on DeltaLima's answer: They use routes called the NATs (North Atlantic Tracks), which can differ each day depending on weather and wind speeds. Each track is a set of coordinates. A pilot ...
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36 votes

How do hot air balloon pilots avoid collisions?

The perspective on that photo makes it hard to tell, but it looks like many of the balloons are still on the ground. So it's not quite as chaotic as it appears. There is no direct horizontal control....
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  • 5,157
36 votes
Accepted

How do airplanes maintain separation over large bodies of water?

They don't leave ATC services when they enter oceanic airspace, but the service provided is no longer based on radar. Instead separation is maintained by following procedures. For example, that means ...
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  • 74.2k
30 votes

How do hot air balloon pilots avoid collisions?

The balloons just float, there is no thrust so no wake etc. If there is a constant wind, all balloons have exactly the same speed. Only local phenomena can create differences in horizontal relative ...
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  • 57.7k
27 votes

Why cruise at 7000' in an A319?

The only reason for your flight to operate at such low altitude is because it is cheaper for them to do so. As you said it is due to weather, other route/altitude may not be available. They can ...
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  • 7,942
26 votes

What does ATC do during "slow" times?

Traffic is fairly predictable. They operate with more personell during rush hour and with much less at night, so it rarely happens that a controller is idling. During peak times there are separate ...
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  • 2,406
16 votes
Accepted

Why cruise at 7000' in an A319?

It was because they could get there faster on a "TEC route." IFR flights are subject to congestion management at the ARTCC level, which means they have to wait their turn in line to be allowed into ...
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  • 25k
13 votes

Why are both ATC and TCAS tasked to prevent collisions although TCAS takes precedence anyway?

While ATC's primary goal is to prevent collisions, it is also responsible for the efficient movement of aircraft through the airspace. That requires a strategic approach to managing air traffic to get ...
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  • 17.3k
10 votes

If all aircraft were TCAS-equipped, how would this change ATC routines?

Think of the ATC system as the road network, traffic lights, road signs, and police. TCAS is a standalone device in your car that warns you the guy coming at right angles to the intersection in front ...
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  • 104k
10 votes
Accepted

Is the ATC of the lower and upper areas of the Netherlands combined or segregated?

Note that the Netherlands is a bit of a special case. Below FL245, Air Traffic Control is provided by Luchtverkeersleiding Nederland (LNVL, the Dutch Air Traffic Control) and Dutch Mil (Dutch ...
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  • 74.2k
9 votes
Accepted

At what intervals do planes land and take off from Chicago O'Hare?

As a general average, Chicago O'Hare (KORD) seems to do somewhere between 1.5 and 2 operations per minute (so roughly one takeoff or landing every 30-40 seconds). I based this on data from the FAA's ...
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  • 67.2k
9 votes

Can pilots choose runway and landing direction?

Pilots can request a particular runway approach course and landing but in a controlled environment they are at the mercy of ATC. At high traffic (read busy) commercial airports they are unlikely to ...
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  • 95.9k
9 votes

How many private jets land at Heathrow airport per day?

How many private jets land at Heathrow airport per day? None! January 2018 movements, source: CAA Related: Where does an A-lister land when they waft in from paradise? Yes, Luton To try to ...
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  • 67.6k
8 votes
Accepted

Why are both ATC and TCAS tasked to prevent collisions although TCAS takes precedence anyway?

TCAS is sort of a fallback, last-resort system used in case all else fails. TCAS works within the scope of what happens within the next minute or so, and will require the involved aircraft to perform ...
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8 votes
Accepted

Are Air Traffic Flow Management Algorithms mostly based on linear programming techniques?

Linear programming (LP) is an optimization method that finds the highest (or lowest) possible value of a set of linear equations given a number of linear constraints. There are a number of objectives ...
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  • 74.2k
8 votes
Accepted

How is separation managed when there are only two parallel runways in a very busy airport?

With two runways, usually, one is dedicated to arrivals, and the other is dedicated to departures. That's the simplest way to handle separation -- only in-trail separation is involved. That's ...
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  • 126
6 votes
Accepted

What is black routing and red routing?

Here's the history, at least for the US. When I hired on, way back in 1985, the FAA had printers based on IBM Selectric mechanisms. They had a two-color ribbon, red and black, and a typeball with ...
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  • 1,474
6 votes
Accepted

What is the minimum distance allowed between planes in flight, in Europe?

Separation minima in Europe are pretty much identical to the rest of the world, since almost all countries base their aviation regulations on ICAO recommendations. To summarize: The minimum vertical ...
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6 votes
Accepted

Is 1,000ft vertical separation in a sparse airspace increasing risk unnecessarily?

Under usual conditions aircraft pass directly above each other at 1,000 ft vertical separation thousands of times a day and it's never been a problem¹. The autoflight systems can maintain altitude to ...
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  • 54.1k
6 votes
Accepted

Was NextGen simulated/tested against alternatives?

NextGen is an FAA programme that strives to modernise America's air transportation system to make flying safer, more efficient, and more predictable. NextGen is not one technology, product, or goal. ...
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  • 74.2k
5 votes
Accepted

If all aircraft were TCAS-equipped, how would this change ATC routines?

It would not change the ATC system at all, since TCAS and ATC work on completely different levels and have vastly different purposes. We even have an ICAO recommendation clearly stating that ATC ...
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5 votes

What does ATC do during "slow" times?

In the center environment, when sectors within a given area of responsibility are slow, they can be combined so a radar team can work a larger proportion of the airspace. Controllers who are not ...
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  • 1,474
4 votes
Accepted

Is a holding pattern always counter-clockwise?

No. The holding pattern can have any inbound course, and any direction. The holding pattern course/direction, depends on departing/arriving traffic, and many other factors. London Heathrow has a ...
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  • 326
4 votes

Are Air Traffic Flow Management Algorithms mostly based on linear programming techniques?

In Europe, the Network Management uses the Computer-Assisted-Slot-Allocation (CASA) algorithm in the Enhanced Tactical Flow Management System to allocate the departure slots. The CASA algorithm is a ...
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  • 349
4 votes

Is it possible for more than one flight to have the same departure and arrival time slots?

When I was working at the FedEx hub in Memphis the pushback times were scheduled every six minutes from 1:48 to 4:00. That's 22 slots for well over 100 flights, so there were several scheduled in each ...
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  • 27.5k
4 votes
Accepted

Can pilots choose runway and landing direction?

To avoid all the Class this and that stuff, just think of controlled (tower with a clearance required) and uncontrolled airports. If a controlled airport, the runway is assigned by the tower ...
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  • 104k

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