# Chocks - why the wide variances in price?

In a comment to a question about setting the parking brake, @rbp said to just get a set of wheel chocks and use those instead. I was piqued - it never occurred to me you'd need your own, I thought they'd be littered around the tarmac for common use - and did a quick Google Shopping search for "aircraft chocks". I was surprised to see a wide price variance, even within a subset of relatively small-size chocks.

For instance, here is a pair of 10" rubber chocks with 3ft rope, about 15 lbs, for \$15. Here is what looks like exactly the same thing, for \$98. Tigerchocks make considerably lighter ones, but they are \$120-ish per chock (over \$200 for any roped pair) while other lightweight designs are as cheap as \$30 for about the same size. Other designs seem to vary between$20-60 for a roped pair, and have noticeable differences in size and design, but c'mon, they're a wedge you put under the tire to stop the plane rolling.

How much of this variance is "you get what you pay for" (more money equals a better product in some way; lighter, grippier, more durable etc) and how much of this is "caveat emptor" (the aviation crowd are used to paying a lot for their gear, so some yahoo with an MBA says "let's see how much we can milk them for a pair of rubber blocks tied with a rope")?

The point of wheel chocks is to prevent the tire from rolling (and thus the aircraft from winding up "somewhere other than where we parked it). The aircraft doesn't know how much we spent on the chocks, and if it did it probably wouldn't care. (OK, it might laugh at you if you buy solid gold bars to chock a Cessna 150.)

Aside from pretty obvious quality-related things (a $5 set of chocks made out of cheap rubber that fall apart when you squeeze them in your hand) the big reasons for price differences come down to a few things: ## Size Just like with chocking a car or truck there are various sizes of chocks available, and they vary in length and height: For very large aircraft very large chocks are used (wider and taller): …and for smaller aircraft smaller chocks are used (shorter and narrower): Big chocks require more material, and thus cost more to make than small chocks, so logically they cost more. ## Nice Features & Laziness I have a set of$20 aluminum wheel chocks. They have a bungee cord that keeps them tight against the tire (so there's no room for the tire to roll), and they weigh just over 1 pound (they're light and small enough to throw in the plane without thinking about it).

The guy two planes down from me has a wheel chock made of three sections of 2-by-4 inch lumber, screwed together to be just slightly wider than his tires and painted safety-orange. It probably weighs less than 5 pounds and cost him \$10 and a few minutes with a power drill & spraypaint.

Both work equally well, but I was willing to pay for someone else to cut and bend some aluminum that I can fold up into a small space easily rather than finding a chunk of lumber I didn't need and making my own chock.

## "Standard Aviation Markup"

There's a joke that when trying to determine the price of a component for an aircraft you take the price of that component in a non-aviation application and add some zeros to the end of it.
That's not a joke in this case: Those two rubber chocks you posted are, for all practical purposes, identical - with the exception of their price.

• Good answer as always. I was going to ask about the feasibility of homemade chocks; didn't know what kinds of FAA or ASTM ratings might be required of something like this that might justify the cost, when you could make practically the same thing out of an old fence post with a chop saw. Jul 20 '15 at 21:28
• @KeithS the basic criteria I personally have for chocks are that they be at least as wide as the tire (preferably a little wider), and "tall enough that you can't roll over them". The latter is important for those nice light aluminum chocks (if you roll over a bent angle of aluminum you may well squish it flat - or at least flat enough that it's a less effective chock and you can roll over it easier next time). Jul 20 '15 at 21:38
• It's probably worth pointing out that the military chocks shown here are just wood (a length of nominal 4x4 or 6x6, depending on the wheel size, with a chamfer) and rope. They're used for short-term use on the tarmac and inside hangars; much more substantial metal chocks are used for longer periods outdoors. Jul 21 '15 at 9:40
• @StanRogers Yeah, I couldn't find any other good pictures of "large airplane" chocks that weren't all watermarked & hard to see what was going on. The main point is to show that the chock blocks the entire face of the whee/truck (as opposed to just being a little pebble that the tire can roll over) Jul 21 '15 at 15:31