What Would Happen If a Plane Flew Too High?

iStock
iStock

Tom Farrier:

People have done this, and they have died doing it. For example, in October 2004, the crew of Pinnacle Airlines 3701 [PDF]  was taking their aircraft from one airport to another without passengers—a so-called "repositioning" flight.

They were supposed to fly at 33,000 feet, but instead requested and climbed to 41,000 feet, which was the maximum altitude at which the aircraft was supposed to be able to be flown. Both engines failed, the crew couldn't get them restarted, and the aircraft crashed and was destroyed.

The National Transportation Safety Board determined that the probable causes of this accident were: (1) the pilots’ unprofessional behavior, deviation from standard operating procedures, and poor airmanship, which resulted in an in-flight emergency from which they were unable to recover, in part because of the pilots’ inadequate training; (2) the pilots’ failure to prepare for an emergency landing in a timely manner, including communicating with air traffic controllers immediately after the emergency about the loss of both engines and the availability of landing sites; and (3) the pilots’ improper management of the double engine failure checklist, which allowed the engine cores to stop rotating and resulted in the core lock engine condition.

Contributing to this accident were: (1) the core lock engine condition, which prevented at least one engine from being restarted, and (2) the airplane flight manuals that did not communicate to pilots the importance of maintaining a minimum airspeed to keep the engine cores rotating.

Accidents also happen when the "density altitude"—a combination of the temperature and atmospheric pressure at a given location—is too high. At high altitude on a hot day, some types of aircraft simply can't climb. They might get off the ground after attempting a takeoff, but then they can't gain altitude and they crash because they run out of room in front of them or because they try to turn back to the airport and stall the aircraft in doing so. An example of this scenario is described in WPR12LA283.

There's a helicopter version of this problem as well. Helicopter crews calculate the "power available" at a given pressure altitude and temperature, and then compare that to the "power required" under those same conditions. The latter are different for hovering "in ground effect" (IGE, with the benefit of a level surface against which their rotor system can push) and "out of ground effect" (OGE, where the rotor system supports the full weight of the aircraft).

It's kind of unnerving to take off from, say, a helipad on top of a building and go from hovering in ground effect and moving forward to suddenly find yourself in an OGE situation, not having enough power to keep hovering as you slide out over the edge of the roof. This is why helicopter pilots always will establish a positive rate of climb from such environments as quickly as possible—when you get moving forward at around 15 to 20 knots, the movement of air through the rotor system provides some extra ("translational") lift.

It also feels ugly to drop below that translational lift airspeed too high above the surface and abruptly be in a power deficit situation—maybe you have IGE power, but you don't have OGE power. In such cases, you may not have enough power to cushion your landing as you don't so much fly as plummet. (Any Monty Python fans?)

Finally, for some insight into the pure aerodynamics at play when airplanes fly too high, I'd recommend reading the responses to "What happens to aircraft that depart controlled flight at the coffin corner?"

This post originally appeared on Quora. Click here to view.

Celebrate the Holidays With the 2020 Harry Potter Funko Pop Advent Calendar

Funko
Funko

Though the main book series and movie franchise are long over, the Wizarding World of Harry Potter remains in the spotlight as one of the most popular properties in pop-culture. The folks at Funko definitely know this, and every year the company releases a new Advent calendar based on the popular series so fans can count down to the holidays with their favorite characters.

Right now, you can pre-order the 2020 edition of Funko's popular Harry Potter Advent calendar, and if you do it through Amazon, you'll even get it on sale for 33 percent off, bringing the price down from $60 to just $40.

Funko Pop!/Amazon

Over the course of the holiday season, the Advent calendar allows you to count down the days until Christmas, starting on December 1, by opening one of the tiny, numbered doors on the appropriate day. Each door is filled with a surprise Pocket Pop! figurine—but outside of the trio of Harry, Hermione, and Ron, the company isn't revealing who you'll be getting just yet.

Calendars will start shipping on October 15, but if you want a head start, go to Amazon to pre-order yours at a discount.

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.

Are Halloween Pumpkins Edible?

Diane Helentjaris, Unsplash
Diane Helentjaris, Unsplash

When people visit their local family-owned pumpkin patch around Halloween, they aren’t usually looking for dinner. The majority of the nearly 2 billion pounds of pumpkins cultivated in the U.S. each year are carved up instead of eaten, making the squash a unique part of the agriculture industry. For people who prefer seasonal recipes to decorations, that may raise a few questions: Are the pumpkins sold for jack-o’-lanterns different from pumpkins sold as food? And are Halloween pumpkins any good to eat?

The pumpkins available at farms and outside supermarkets during October are what most people know, but that’s just one type of pumpkin. Howden pumpkins are the most common decorative pumpkin variety. They’ve been bred specifically for carving into jack-o’-lanterns, with a symmetrical round shape, deep orange color, and sturdy stem that acts as a handle. Shoppers looking for the perfect carving pumpkin have other options as well: the Racer, Magic Wand, Zeus, Hobbit, Gold Rush, and Connecticut field pumpkin varieties are all meant to be displayed on porch steps for Halloween.

Because they’re bred to be decoration first, carving pumpkins don’t taste very good. They have walls that are thin enough to poke a cheap knife through and a texture that’s unappealing compared to the squashes consumers are used to eating. “Uncut carving pumpkins are safe to eat; however, it's not the best type to use for cooking,” Daria McKelvey, a supervisor for the Kemper Center for Home Gardening at the Missouri Botanical Garden, tells Mental Floss. “Carving pumpkins are grown for their large size, not the flavor. Their flesh can be bland and the fibers are very stringy.”

To get the best-tasting pumpkins possible this autumn, you’re better off avoiding the seasonal supermarket displays. Many pumpkin varieties are bred especially for cooking and eating. These include Sugar Pie, Kabocha, Jack-Be-Little, Ghost Rider, Hubbard, Jarrahdale, Baby Pam, and Cinderella pumpkins. You can shop for these varieties by name at local farms or in the produce section of your grocery store. They should be easy to tell apart from the carving pumpkins available for Halloween: Unlike decorative pumpkins, cooking pumpkins are small and dense. This is part of the reason they taste better. McKelvey says. “[Cooking pumpkins] are smaller, sweeter, have a thicker rind (meatier), and have less fibers, making them easier to cook with—but not so good for carving.” These pumpkins can be stuffed, blended into soup, or simply roasted.

If you do want to get some culinary use out of your carving pumpkins this Halloween, set aside the seeds when scooping out the guts. Roasted with seasonings and olive oil, seeds (or pepitas) from different pumpkin varieties become a tasty and nutritious snack. Another option is to turn the flesh of your Halloween pumpkin into purée. Adding sugar and spices and baking it into a dessert can do a lot to mask the fruit’s underwhelming flavor and consistency.

Whatever you do, make sure your pumpkin isn’t carved up already when you decide to cook with it. There are many ways to recycle your jack-o’-lanterns, but turning them into pie isn’t one of them. "If one does plan on cooking with a carving pumpkin, it should be intact,” McKelvey says. “Never use one that's been carved into a jack-o'-lantern, otherwise you could be dealing with bacteria, dirt and dust, and other little critters.”