flying by the seat of sb's pants

気になる表現がありました。

Here’s a possible deal for last-minute 4th of July planners who enjoy flying by the seat of their pants — or rather, by private plane. As Robb Report alerts us, on July 3, aircraft charter company JetSuite will release a certain number of $4 one-way fares.

The catch? Travel is on Independence Day only.

JetSuite’s normal one-way rates start at $536 for up to four people (not a terrible price at all), but it’s pretty awesome to think of taking off for the cost of a couple of red, white and blue party hats — which you’ll definitely want to bring on board if you score this deal.

If you’d like the chance to snap up a bargain chartered aircraft, which could be a four-seat Embraer Phenom 100 or a Cessna Citation CJ3 six-seater, toggle over to JetSuite.com and complete the free registration for SuiteDeals. After you add your info, JetSuite will alert you via text or email when deals are available from your desired takeoff airports (to destinations in the U.S., Mexico, and Caribbean), including any $4 fares that open up on July 3.

Sure, you’re probably likelier to blast your eye out with a firework than actually qualify for one of these prices, but you never know. It might be worth getting a few JetSuite texts for the next week to chance it, assuming you’re the kind of person who can hang with super-duper last-minute travel. Thanks to the wonders of private air travel, you’d only have to show up 15 minutes early for the flight — so that’s more time to pack.

http://roadwarriorvoices.com/2015/06/25/charter-a-private-jet-for-4-on-july-4th/

とりあげる表現は“flying by the seat of their pants”です。『ジーニアス英和辞典第5版』（大修館書店）によると「(fly) by the seat of one’s pants：（困難・危険だが）自分の技術［経験］を頼りに（行動する）」とありました。見た目では意味合いが理解できなかったので語源を調べてみると、飛行機に計器や通信機器が発達していなかった時代はお尻を座席にしっかりと着け、そこから伝わる振動や五感から得られる諸々の情報を頼りに操縦していたことに由来していました。ここから、計画なしで物事を進めるという表現になったようです（Chris）