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Summer Flying Series – Dehydration

News > Summer Flying Series – Dehydration

Our summer flying poll showed dehydration tied with low-level wind shear as one of your main concerns during the summer months. Pilots should constantly be aware of the effects of human factors in flight. Many pilots do not realize that lack of hydration can affect their coordination and cognitive abilities. The case studies below are incidents that very well may have been prevented if the pilots were hydrated. Every accident is a chain of missteps or issues and breaking any one of the chains often keeps an incident or accident from happening. In these cases, just being hydrated could have made the difference and broken the unfortunate chain of events.

And, if you’re lucky enough to be at Oshkosh this week, keep in mind that many people become dehydrated while enjoying the airshow.  As you prepare for arrival and/or departure at Oshkosh, remain cognizant of the need to continually hydrate.  It takes time to rehydrate, so plan accordingly.

Case Studies

[The following are excerpts from NTSB Accident Number: WPR11LA260]

On June 13, 2011, about 1825 pacific daylight time, a Grumman G-164A, N5286 sustained substantial damage when it departed the runway and collided with two dumpsters at a private airstrip in Buttonwillow, California. Visual meteorological conditions prevailed and no flight plan was filed. The commercial pilot was not injured. The flight originated from a private field in Buttonwillow, California at 1000.

 The pilot stated that on the day of the accident he had conducted numerous landings on the accident airstrip and the brakes were “a little worn out,” but had operated well enough to allow stopping on the runway. The pilot further stated that he was fatigued and dehydrated after flying for nearly 8 hours. On the accident landing the pilot reported that he was slightly fast on the approach with a tailwind of approximately 5-10 knots. Upon touchdown he was unable to stop the airplane before the end of the runway and exited the right side. After the airplane exited the runway the airplane’s right wing struck a dumpster. The initial impact with the dumpster caused the airplane to spin into a second dumpster with which the airplane came to rest against. Immediately after the accident the owner/operator checked the brakes and found them to be operating normally.

 The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot’s misjudgment of the landing approach and subsequent long landing and overrun of the runway resulting in a collision with ground obstacles. Contributing to the accident was the pilot’s likely fatigue and dehydration.

[The following are excerpts from NTSB Accident Number: DEN99LA102]

On June 10, 1999, approximately 1520 mountain daylight time, a Schweizer SGU-2-22E, N5823V, was substantially damaged when it collided with terrain during landing approach at Hobbs, New Mexico.

The pilot said his tow aloft had been ‘fairly rough,’ and he released at 2,000 feet, in turbulence, and ascended in a thermal to 5,000 feet. He was ‘frustrated’ by the turbulence, and was ‘having trouble controlling the plane,’ so he decided to land. He began to get ‘frustrated and nervous’ and started ‘breathing really hard because [he] was scared.’ He began to ‘feel strange,’ and his face and hands ‘felt numb. . .like they had fallen asleep.’ He began to see ‘a lot of little dots,’ and he ‘passed out.’ He regained consciousness just before striking a stop sign. He flew under some powerlines, then landed in a field, and struck a pole embedded in the ground.

Although the pilot was uninjured in the accident, he was transported to the Lea Regional Medical Center where he was examined and released. The pilot’s parents signed a release and their son’s medical records were given to an FAA inspector. The physician who examined the pilot told CAP officials that he was dehydrated. This, with his hyperventilating, probably caused the brief lapse of consciousness. The official diagnosis was “vasovagal syncope.”

The National Transportation Safety Board determines the probable cause(s) of this accident to be: Pilot incapacitation (loss of consciousness) due to dehydration and hyperventilation. Factors were the turbulence and excessive workload (task overload) that induced anxiety/apprehension, and striking the sign and the pole.

What is Dehydration?

Dehydration is the excessive loss of water from the body, as from illness or fluid deprivation. This fluid loss can occur in any environment, so just because it isn’t a hot day or you aren’t at high altitude, that doesn’t mean you can’t become dehydrated.

What Causes Dehydration?

Hot aircraft cabins, wind, humidity, diuretic drinks (e.g., coffee, tea, cola), sunburn, and improper attire can lead to pilots becoming dehydrated.

Some Common Signs and Symptoms of Dehydration

Common symptoms include headache, fatigue, cramps, sleepiness, dizziness, and, in severe cases, lethargy and coma.  Any of these symptoms can place pilots at increased risk for incidents and accidents.

Heat Exhaustion

Heat exhaustion is the body’s response to an excessive loss of water and salt, usually through excessive sweating.

Heat Exhaustion Often Accompanies Dehydration

There are 3 stages to heat exhaustion:

  1. Heat stress (body temp. 99.5°-100° F) – reduces performance, decision-making ability, alertness, and visual capabilities. Symptoms may linger for up to 48 hours.
  2. Heat exhaustion (body temp. 101°-104° F) – fatigue, nausea/vomiting, cramps, rapid breathing, and fainting.
  3. Heat stroke (body temp. ≥105° F)
  • Heat stroke occurs when the body the body’s temperature rises rapidly, the sweating mechanism fails, and the body is unable to cool down. Effectively, the body can no longer control its temperature. This usually happens at a body temperature of 106° F or higher.
  • Mental confusion, disorientation, and coma occurs. Heat stroke can cause permanent disability or death if the person does not receive emergency treatment.

How to Avoid Dehydration and Heat Exhaustion

Every person is physiologically different, so the following are suggestions. Every pilot should know their constitution and adjust these suggestions to their particular circumstances and bodies.

Do not wait to drink water until you are thirsty. Most people have the urge to drink water when they are already at a 1.5-quart (about 1.4 liters) water deficiency. At this level of dehydration, one’s body gives the signal of being thirsty. So when you have this feeling, you’re already behind the 8-ball. Further, a small amount of water may allow you to become less than a 1.5-quart (about 1.4 liters) deficiency, but you can still be dehydrated without continuing to trigger the thirst feeling. Therefore, the sense of thirst should not be your primary instrument, but rather being thirsty should be your “stall warning,” where you never want to be surprised that the thirst warning is going off.

In general, you need to drink between 2 to 4 quarts (about 1.9 to 3.8 liters) of water every day. The old adage was to drink 8 glasses of water a day, which equates to 2 quarts (about 1.9 liters). However, this is the low range. Many people need to drink more than 8 glasses per day.

Here are some more general guidelines:

  • Drink cool water, but not ice-cold water. If you don’t like the bland taste of water, try adding lime juice to your water.
  • Limit your daily intake of caffeine and alcohol (both are diuretics).
  • Properly acclimate to major weather and/or climate changes.
  • Choose appropriate attire for the forecast conditions.
  • Monitor your physical activities, such as how recently you have exercised.
  • Consider whether you have had a recent illness, such as fever, vomiting, or diarrhea.

Finally, if you feel lightheaded or dizzy, it’s always best to stay on the ground and get hydrated.

Be Aware Heat that Exhaustion is Possible When Hydrated

Even if you are drinking plenty of water, there are instances where external water intake cannot keep pace with the loss of fluids. If you have ever flown in the southwest, such as Arizona during the summer, you’ve experienced this. When the temperature is 115+ degrees Fahrenheit, it’s nearly impossible to stay hydrated while flying in an unairconditioned aircraft.

What Should You Have Learned?

Dehydration can affect your cognitive and coordination abilities. If dehydration persists, it can get worse and lead to heat exhaustion, or worse, heat stroke. Be proactive in your hydration practices and know that having the feeling of being thirsty is an indication that you are already dehydrated, typically by about 1.5 quarts (or 1.4 liters). To prevent dehydration, one should drink 2 to 4 quarts (about 1.9 to 3.8 liters) of water a day to prevent dehydration. In addition to drinking water, you can help prevent dehydration by limiting your daily intake of caffeine and alcohol, properly acclimating to major weather and/or climate changes, choosing appropriate attire for the forecast conditions, monitoring your physical activities, and being self-aware if you have had a recent illness, such as fever, vomiting or diarrhea.

So, whether we get a chance to see you at Oshkosh this summer or not, stay safe, and stay hydrated.

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