Why Florida Keys have a minimum safe altitude of 14,200 feet?

2018-03-10 [Petri]

Florida is flat as a pancake: especially around Florida Keys - driving towards Key West, you'll notice that the road surface is just a couple of meters above the sea level at its highest.

This same flatness is reflected in VFR (Visual Flying Rules) flying above Florida, too: the aviation chart has a minimum safe altitude of only 700 feet for the Keys area, so buzzing around in 1,000-2,000 feet will provide a very scenic experience.

But when you pass Marathon Key and Seven Mile Bridge on your way to Key West, the safe altitude suddenly jumps to 14,200 feet. So to be safe from obstacles, you should be flying so high that you would need to use supplementary oxygen in a non-pressurized airplane.

Why?

You may have spotted the reason for this when you approach this area: there is a stationary blimp in the air just north of the US Route 1, also known as the Overseas Highway.

This is a military installation, containing special radar equipment inside the blimp, locally known as "Fat Albert", with the aim of detecting any low-flying traffic approaching the United States airspace, and the cable that ties it to the ground causes the sudden jump of the minimum safe altitude.

It is technically known as Tethered Aerostat Radar System (TARS), and last year it even seemed to have spawned a smaller one next to it.

I have never seen the actual cable that obviously is needed to connect the blimp to the ground, and the invisibility of it is THE problem, as it would be potentially lethal if flown into.

Even if you survived the collision and only let the blimp loose by cutting the cable, you can be sure that Uncle Sam would come very hard on you, as their secret, multi-million dollar military hardware would float to God knows where with the prevailing easterly winds.

This simple example shows that it pays to study the regional aviation maps before embarking on leisure flights even in places that appear to be completely harmless.

The Keys area has often very interesting weather from the pilot's point of view: flying around the puffy cumulus formations over the beautiful scenery is great fun, but unless you do your homework, your leisure flight could turn lethal.

First thing to remember, though, is that due to the beauty of the region and the abundance of private pilots in Florida, there are plenty of others over the same narrow Keys, so keep your eyes peeled for traffic and listen to the radio traffic, also informing others of your intentions when approaching the airports in the region.

Another thing to remember here is that before you actually reach Key West, you have to pass through the airspace of the Boca Chica Navy Station. So remember to contact "Navy Tower" at 118.575 MHz and ask for a permission to traverse their airspace. You don't want the consequences of crossing military airspace without permission, especially during weekdays when there's often several F-18's buzzing around.

If you aim to follow the Overseas Higway on the way back, you need to make the same request again, and as Boca Chica is right next to Key West airport, this makes departing and approaching KEYW a busy radio experience.

And why is the blimp at 14,000 feet? Because the Earth is round, and this altitude gives you a "over-the-horizon" view of the lower airspace and sea around the Keys, providing more time to send a fighter jet to intercept any approaching traffic.

What the blimp actually contains is naturally a military secret, but here's a Wikipedia article on TARS that gives you an overview of the radar setup.

Permalink: https://bhoew.com/blog/en/4

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