Inter-Island Flights

While vacationing in St. Maarten, I plan to do a day trip to Saba, with the intention of doing 3 dives. I would fly out in the morning, returning in the evening. The first dive would be at 90 to 130 ft., and the two subsequent dives at 70 to 80 ft. or shallower. The dive operator has assured me that it would be safe to fly back, that same day, as the aircraft would only reach an altitude of 2000 ft. for a few minutes during the 12 minute return flight. Will it be safe to fly under these conditions and is 2000 ft. the cut-off altitude for flying after diving?
You are asking about a pattern of exposure for which there is very limited empirical data. The guidelines in this low altitude range are cobbled together from a combination of expert opinion and whatever research can reasonably be applied. Knowing that there is a high likelihood of some degree of vertical travel post-dive (with no huge problem being identified) and appreciating the implications of research data from Switzerland based on 1700 ft exposures, the 2002 Divers Alert Network flying after diving guidelines stipulated a cabin altitude within the 2,000-8,000 ft range. Lesser altitudes are excluded. Alternatively, the US Navy flying after diving table (9-6) begins with an altitude table of 1000 ft although it only applies minimum surface interval penalties for high repetitive groups.
While the above may seem promising, the dives you propose to do could easily achieve extremely high post-dive repetitive groups. The remaining wild cards are the flight altitude and duration. I believe that the inter-island flights in that region are frequently below 2500 ft, below 2000 ft may be common but certainly not guaranteed. Weather and traffic conditions might well prolong flight time or result in a higher flight altitude and/or a lower atmospheric pressure for any given altitude. The person giving you the advice was describing an optimal case which may or may not be realistic.
Ultimately, the overall risk in the day you describe is probably fairly small, but it is certainly not a plan I would encourage or choose to do for recreation. The 'cutoff' guaranteeing safety that you were hoping for simply does not exist. The net risk is determined by multiple factors - those directly concerning the diving (depth, time, thermal stress, exertion level, post-dive surface interval), environmental conditions (weather, atmospheric pressure, geography), pilot discretion, other air traffic, and individual susceptibility. You are planning to stack enough variables against safety that a few other factors going in the wrong direction could end up producing a bad day.
Safety margins could be added through the use of nitrox with a decompression algorithm set to air (but you would have to be very cautious in respecting the maximum limits of the mix in your deeper dives) and/or diving more conservative profiles and/or delaying the return time. The problem with planning such an ambitious day, though, is that, once set in motion it is hard to stop. And, again, a compromise here or there or in any number of ways could easily end up producing in a bad day.
Ultimately, you have to decide what risk you are willing to take. If you are not diving alone, you partner or partners would have to make similar decisions. In thinking of this, remember that decompression insults tend to be probabilistic events. Getting away with something once, twice or ninety-nine times does not make it safe. My advice is to focus on all the ways to increase your margin of safety so that good habits can make diving as worry-free as an enjoyable activity should be.
Neal W. Pollock, Ph.D.
While the above may seem promising, the dives you propose to do could easily achieve extremely high post-dive repetitive groups. The remaining wild cards are the flight altitude and duration. I believe that the inter-island flights in that region are frequently below 2500 ft, below 2000 ft may be common but certainly not guaranteed. Weather and traffic conditions might well prolong flight time or result in a higher flight altitude and/or a lower atmospheric pressure for any given altitude. The person giving you the advice was describing an optimal case which may or may not be realistic.
Ultimately, the overall risk in the day you describe is probably fairly small, but it is certainly not a plan I would encourage or choose to do for recreation. The 'cutoff' guaranteeing safety that you were hoping for simply does not exist. The net risk is determined by multiple factors - those directly concerning the diving (depth, time, thermal stress, exertion level, post-dive surface interval), environmental conditions (weather, atmospheric pressure, geography), pilot discretion, other air traffic, and individual susceptibility. You are planning to stack enough variables against safety that a few other factors going in the wrong direction could end up producing a bad day.
Safety margins could be added through the use of nitrox with a decompression algorithm set to air (but you would have to be very cautious in respecting the maximum limits of the mix in your deeper dives) and/or diving more conservative profiles and/or delaying the return time. The problem with planning such an ambitious day, though, is that, once set in motion it is hard to stop. And, again, a compromise here or there or in any number of ways could easily end up producing in a bad day.
Ultimately, you have to decide what risk you are willing to take. If you are not diving alone, you partner or partners would have to make similar decisions. In thinking of this, remember that decompression insults tend to be probabilistic events. Getting away with something once, twice or ninety-nine times does not make it safe. My advice is to focus on all the ways to increase your margin of safety so that good habits can make diving as worry-free as an enjoyable activity should be.
Neal W. Pollock, Ph.D.
Posted in Dive Safety FAQ
Categories
2020
January
February
Group Fitness at the PoolHow to Rescue a Distressed diver at the SurfaceHow to manage Near-DrowningNo Sit-ups no problem How to manage MalariaHow to manage Oxygen Deficiency (Hypoxia)What to do when confronted by a sharkHow to manage Scombroid PoisoningHow to perform a Deep Diver RescueHow to perform One-rescuer CPRHow to perform a Neurological Assessment
March
DAN’s Quick Guide to Properly Disinfecting Dive GearCOVID-19 : Prevention Recommendations for our Diving CommunityGermophobia? - Just give it a reasonable thoughtScuba Equipment care – Rinsing and cleaning diving equipmentCOVID-19 and DAN MembershipFurther limitations imposed on travels and considerations on diving activitiesDAN Membership COVID-19 FAQsLancet COVID-19 South African Testing SitesCOVID-19 No Panic Help GuideGetting Decompression Sickness while FreedivingDown in the DumpsCardiovascular Disease and DivingDelayed Off-GassingDiving after Dental surgeryDiving with Multiple MedicationsPygmy Seahorses: Life AquaticAfrica DustCOVID-19 Myth BustersScuba Units Are Not Suitable Substitutes for VentilatorsDisinfection of Scuba Equipment and COVID-19Physioball Stability Exercises
April
COVID-19 AdvisoryScuba Equipment Care - Drying & Storing Your GearTransporting Diving Lights & BatteriesHow to Pivot Your Message During a CrisisTourism Relief FundCOVID-19 Business Support ReviewDiving After COVID-19: What We Know TodayEUBS-ECHM Position Statement on Diving ActivitiesPart 2: COVID-19 Business Support ReviewPress Release
May
Diving in the Era of COVID-19Dive Operations and COVID-19: Prepping for ReturnCOVID-19 & Diving Activities: 10 Safety RecommendationsCOVID-19: Surface Survival TimesThe Philippines at its FinestThe Logistics of ExplorationThe Art of the Underwater SelfieShooter: Douglas SeifertFAQs Answered: Disinfecting Scuba EquipmentStock your First-Aid KitResearch and OutreachCovid-19 ResearchOut of the BlueEffects of Aspirin on DivingThe New Pointy end of DivingDiving and Hepatitis CCaissons, Compressed-Air work and Deep TunnellingPreparing to Dive in the New NormalNew Health Declaration Form Sample Addressing C-19 IssuesDiving After COVID 19: What Divers Need to Know
June
Travel Smarter: PRE-TRIP VACCINATIONSAttention-Deficit/Hyperactivity Disorder and DivingCOVID-19: Updated First Aid Training Recommendations From DANDiving with a Purpose in National Marine SanctuariesStay Positive Through the PandemicFor the Dive Operator: How to Protect Your Staff & ClientsStudying Deep reefs and Deep diversAsking the Right QuestionsLung squeeze under cold diving conditions
July
Dive DeprivationVolunteer Fish Surveys: Engage DiversDAN Member Profile: Mehgan Heaney-GrierTravel Smarter: Don’t Cancel, Reschedule InsteadDive Boat Fire SafetyRay of HopePartner ExercisesDiving at AltitudeAluminium ExposureHip FracturesAcoustic NeuromaGuidelines for Lifelong Medical Fitness to DiveNew Dive Medical Forms
August
Women in Diving: Lauren Arthur, Conservationist & Natural History Story TellerWomen in Diving: Dr Sara Andreotti White Shark ResearcherTiming ExerciseWomen in Diving: The Salty Wanderer, Charlie WarlandWomen in Diving: Beth Neale, Aqua soul of freedivingWomen in Diving: Diving and spearfishing Diva, Jean HattinghWomen in Diving: Zandile Ndhlovu, The Black Mermaid
September
October
Freediving For ScienceStep Exercises with CardioFluorescence Imaging help Identify Coral BleachingChildren and DivingThe Watchman device and divingScuba Diving and Factor V Leiden gene mutationNitrogen Narcosis at shallow depthsOil and Particulates: Safe levels in Breathing Air at depthDive Principles for Coping with COVID-19The Importance of a Predive Safety CheckTalya Davidoff: the 'Plattelandse Meisie' Freediver
2019
February
April
May
DAN Press ReleaseYour Dive Computer: Tips and tricks - PART 1Your Dive Computer: Tips and tricks - PART 2Aural HygieneDCS AheadHow Divers Can Help with coral conservationRed Tide and shellfish poisoningDiving after Kidney DonationDiving with hypertrophic cardiomyopathyEmergency Underwater Oxygen Recompression
June
July
September
October
November
Exercise drills with DowelsHeart-rate TrainingCultivating ConservationTRavel Smarter : Evaluating an unfamiliar Dive operatorChallenging the Frontiers of Decompression ResearchTravel Smarter: Plan for Medical EmergenciesWhen should I call my Doctor?DAN Student Medical Expense CoverageAdvice, Support and a LifelineWetsuits and heat stressDiving after Chiropractic adjustments
2018
April
Flying after pool diving FAQLung squeeze while freediving FAQDiving after Bariatric surgery FAQMarine injuries FAQVasovagal Syncope unpredictable FAQIncident report procedure FAQDiving after knee surgery FAQDiving when in RemissionDive with orbital Implant FAQInert gas washout FAQOxygen ears FAQPost Decompression sicknessChildren and diving. The real concerns.Diving after SurgeryPhysiology of Decompresssion sickness FAQDiving and regular exerciseGordon Hiles - I am an Underwater Cameraman and Film MakerScuba Air QualityBreath-hold diving. Part 3: The Science Bit!Compensation Legislation and the Recreational DiverCape Town DivingFive pro tips for capturing better images in cold waterThe Boat Left Without You: Now What?
May
When things go wrongEmergency Planning: Why Do We Need It?Breath-hold diving: Running on reserve -Part 5 Learning to RebreatheSweet Dreams: When Can I Resume Diving Post Anaesthesia?Investing in the future of reefsTo lie or not to lie?THE STORY OF A RASH AFTER A DIVEFirst Aid KitsTaravana: Fact or Falacy?
June
Oxygen Unit MaintenanceKnow Your Oxygen-Delivery Masks 1Know Your Oxygen-Delivery Masks 2Emergency Oxygen unitsInjuries due to exposure - HypothermiaInjuries due to exposure - Altitude sicknessInjuries due to Exposure - Dehydration and other concernsHow to plan for your dive tripThe Future of Dive MedicinePlastic is Killing our ocean
September
Return to DivingDiagnoses: Pulmonary blebSide effects of Rectogesic ointmentDiving with ChemotherapyReplacing dive computers and BCDsCustomize Your First-Aid KitPlan for medical emergenciesHow the dive Reflex protects the brain and heartDry suits and skin BendsAltitude sickness and DCSScuba Diving and Life Expectancy
2017
March
April
Incident Insight: TriageA Field Guide to Minor MishapsSnorkels: Pros & ConsTime & RecoveryMedication & Drug UseDiving with CancerNitrox FAQCOPD FAQHyperbaric Chamber FAQJet Lag FAQHydration FAQAnticoagulant Medication FAQFluid in the Ear FAQEye Surgery FAQElderly Divers FAQNitrogen FAQHealth Concerns FAQMotion Sickness FAQMicronuclei FAQ
June
August
2016
February
March
Breath-Hold Diving & ScubaReturn to Diving After DCITiming Exercise & DivingHot Tubs After DivingSubcutaneous EmphysemaIn-Water RecompressionDiving at AltitudeFlying After DivingDiving After FlyingThe Risks of Diabetes & DivingFlu-like Symptoms Following a DiveHand & Foot EdemaFrontal HeadachesBladder DiscomfortLatex AllergiesRemember to BreatheProper Position for Emergency CareAches & PainsCell Phones While DrivingSurfers Ear Ear Ventilation TubesDealing with Ear ProblemsDiving with Existing Ear InjuriesPerforated Ear DrumENT SurgeryUnpluggedCochlear ImplantsPortuguese Man-of-WarJellyfish StingsLionfish, Scorpionfish & Stonefish EnvenomationsStingray Envenomation Coral Cuts, Scrapes and RashesSpeeding & Driving Behaviour
June
Newsflash! Low Pressure Hose DeteriorationItching & rash go away & come back!7 Things we did not know about the oceanMigraine HeadacheAttention Deficit Disorder Cerebral Vascular AccidentEpilepsyCerebral PalsyHistory of SeizuresMultiple Sclerosis Head TraumaBreast Cancer & Fitness to Dive IssuesLocal Allergic ReactionsSea LiceHow ocean pollution affects humans Dive Fatality & Lobster Mini-Season StatisticsPregnancy & DivingReturn to Diving After Giving BirthBreast Implants & DivingMenstruation During Diving ActivitiesOral Birth ControlBreast FeedingPremenstrual SyndromeOsteoporosisThe Aftermath of Diving IncidentsCompensation Legislation & the Recreational DiverNoise-Induced Hearing LossLegal MattersThe Nature of Liability & DivingDAN Legal NetworkWaivers, Children & Solo DivingHealthy, but overweight!Taking Medication while Scuba DivingGetting Fit for the Dive SeasonBone Considerations in Young DiversAsthma and Scuba DivingHepatitisDiving with HyperglycemiaShoulder PainDiving After Spinal Back Surgery
August
Hazard Identification & Risk AssessmentCaring For Your People Caring For Your FacilitiesCaring For Your BusinessScuba Air Quality Part 1Scuba Air Quality Part 2Chamber Maintenance Part 1Chamber Maintenance Part 2The Aging Diver Propeller SafetyRelease The PressureDon't Get LostMore Water, Less Bubbles13 Ways to Run Out of Air & How Not To7 Mistakes Divers Make & How To Avoid ThemSafety Is In The AirHow Good Is Your Emergency Plan
2015
January
March
No Comments