Many divers fly home after a diving holiday, but how many realise that this might have consequences and there are guidelines on how long they should wait? We often see divers at the hyperbaric unit who clearly have not waited long enough before flying and have developed decompression illness during the flight. Thankfully these are a tiny minority of divers and are not usually severe cases, but time to treatment is often delayed and can result in residual symptoms.
Why do we decompress during a flight? Commercial aircraft are pressurised to less than an atmosphere for a number of reasons, primarily financial. No planes are airtight and therefore leak. This requires compressors to maintain cabin pressure, which requires expensive fuel. However the pressurised plane is then heavier and this requires more fuel too. Therefore pressurising the fuselage to less than 1 atmosphere makes flying cheaper and we all decompress on the flight home. This is not a problem unless you’ve been diving recently. PADI appears to follow the DAN guidelines on flying after diving:
The following guidelines are the consensus of attendees at the 2002 Flying After Diving Workshop. (Alert Diver, November/December 2002, www.diversalertnetwork.org/files/FADWkshpBook_web.pdf) They apply to air dives followed by flights at cabin altitudes of 2,000 to 8,000 feet (610 to 2,438 meters) for divers who do not have symptoms of decompression sickness (DCS). The recommended preflight surface intervals do not guarantee avoidance of DCS. Longer surface intervals will reduce DCS risk further. For a single no-decompression dive, a minimum preflight surface interval of 12 hours is suggested. For multiple dives per day or multiple days of diving, a minimum preflight surface interval of 18 hours is suggested. For dives requiring decompression stops, there is little evidence on which to base a recommendation, and a preflight surface interval substantially longer than 18 hours appears prudent.
In reference to these guidelines, scubadoc states (http://www.scuba-doc.com/flyngaft.htm):
The above is for sports diving and should not apply to commercial diving or nitrox diving. Because of the complex nature of DCS and because decompression schedules are based on unverifiable assumptions, there can never be a fixed flying after diving rule that can guarantee prevention of bends completely.
After treatment for decompression illness, there also should be some time for recovery before flying. Damage from the bubbles of decompression illness is the result of many interactions, but one of the most basic problems is lack of oxygen (low partial pressure of oxygen) in the tissues. Unfortunately a lower partial pressure of oxygen in the tissues also occurs with the decompression and lower cabin pressure involved in commercial flights. Therefore flying after treatment for decompression illness should be discussed with the diving doctor. The US Navy Diving Manual (Rev 6) states: Patients with residual symptoms should fly only with the concurrence of a Diving Medical Officer. Patients who have been treated for decompression illness or arterial gas embolism and have complete relief should not fly for 72 hours after treatment, at a minimum.
Can I fly home immediately after a 40 min Discover Scuba session to 5m?
No. This is a single no decompression dive and you must wait at least 12 hours.
I am going to drive home over some hills that are around 1000ft above sea level. Is this OK within 12hrs of surfacing?
This is probably OK, but be aware that symptoms may still occur,especially if you ascend to altitude sooner rather later after surfacing. Anything below 2000ft (610m) should be fine. There are plenty of hills within the UK that are over this height and I have seen divers develop decompression illness as a result of driving home over the Pennines, for example.
As a diving officer, what should I advise helicopter crews, if a diver requires airlifting to a chamber?
This needs to be discussed on a case by case basis with the diving doctor and the service providing the aircraft as there is a risk of worsening the decompression illness but there are also significant risks to flying low.
Advice usually includes:
Keep the diver on 100% oxygen
Use an aircraft pressurised to 1 atmosphere if available
Fly as low as possible, preferably below 1000ft
I have a commercial diving medical from the Health and Safety Executive, what are their recommendations about return to diving after DCI?
Commercial diving is very different to sports diving, with far more control over depths, times, ascent rates, multilevel diving and number of dives per day. However the diver has less control over when he/she actually dives. Its therefore not really reasonable to compare the two. I would recommend that you discuss it with the diving doctor that treated you. The HSE guidelines can be found at: www.hse.gov.uk/diving/ma1.pdf
Where can I get more advice on flying, diving and decompression illness?
The Divers Emergency Service Telephone: +44 (0) 7999 292 999
We are based at London Hyperbaric Medicine in the East end of London. You can phone us from anywhere in the world and we will help you find your nearest chamber and diving doctor