NAT Operations
Summary
10/23/2024 Read Time: 10 min
The North Atlantic Airspace has specific documentation and record-keeping requirements. Procedural differences for both normal and contingency operations make a NAT crossing unique from domestic operations.
NAT Doc 007 is the primary source of information. The numbered references below point to NAT Doc 007.
Details
Preflight
Oceanic Documents
NAT Doc 007 lists a host of documents needed to complete a crossing (6.2.2)
Master Document (flight plan summary and nav log)
NOTAMs
Weather: Airports, SIG WX charts, PIREPS, Space wx
Oceanic Track Messages
ETPs (Equal Time Points)
Volcanic Ash Information
Plotting Chart
ICAO Flight Plan
Foreflight is your NAT friend. Specifically, a Foreflight Dispatch subscription - especially with Active Navlog. It is a one-stop shop for planning and executing a crossing and adds additional functionality for oceanic ops. When you create a flight within Foreflight, the automatically generated Briefing packet contains most of the above documents.
Your Master Document is an in-flight log that records your progress along a crossing. As you record data over waypoints, you compare your times, fuel burns, and course information. More info on this is forthcoming.
NOTAMs and weather are included in the Foreflight Briefing, and track messages are too if your route is near the Organized Track System. The same is true for volcanic ash information. Foreflight's map has a US IFR Ocean layer that can function as a plotting chart, or you can utilize Foreflight's Active Navlog (preferred) that covers the required record-keeping during and after a crossing. Alternatively, you can purchase a Jeppesen paper chart if you would like to plot your course by hand.
After completing the crossing, you should retain all documents for six months. If there is any investigation, the documents recreate your trip and are your opportunity to show you knew what you were doing over the ocean and did not commit a Gross Navigation Error (GNE). A GNE occurs when you are 10 nm off course.
ETPs, ETOPS, and PSR
Equal Time Points (ETPs) are calculated for emergencies. ETPs along your route indicate which diversion airport is closest timewise. They are decision points about whether to press on or turn back. The diversion airports may be different from your origin or destination.
Three kinds of ETPs are calculated: medical, single-engine failure, and depressurization. Medical is if a passenger or crewmember needs to get to a hospital ASAP. I bet you can guess what the other two are about. They both present a more challenging situation because your planned altitudes and fuel burns could be drastically affected.
Here is the formula for manually figuring ETPs that compares your ground speed to continue versus your ground speed to return:
Ground distance to ETP = (D x GSr) / (GSc + GSr) = nm
Armed with this and a whizz wheel, you can entertain yourself for the whole flight. For everyone else, Foreflight Dispatch has your back. When creating a flight plan in Dispatch, you can specify one or more ETP airport pairs.
For example, on a flight from CYFB (Iqaluit, Canada) to BIRK (Reykjavik, Iceland), your first ETP pair may be CYFB and BGSF (Kangerlussuaq, Greenland), and the second BGSF and BIKF (Keflavik, Iceland). The applicable ETPs for your aircraft would then be in the Briefing packet and Active Navlog. If on paper, you should plot these on your map (include a picture example). Consider each airport's weather, NOTAMs, and ground services when planning ETPs.
The most critical situation is depressurization, which necessitates descending to 10,000ft, flying slower, and burning more fuel. If you run out of fuel at any point before reaching your diversion airport, you have a "wet footprint." This is a big no-no for commercial operations (read CFR 135.381), but under part 91, there is no requirement.
While wet footprint is not an official term, avoiding it means planning your route and fuel load to always have an out and can make it to an alternate, even if you lose an engine or depressurize. It's a plan to keep you out of the drink. Single-engine aircraft will have a wet footprint if operated outside gliding distance from shore. Check out required survival gear here.
Commercial operators must also comply with ETOPS - Engines Turn Or People Swim - a similar but different regulation (CFR 134.364). Okay, it's called Extended Twin-engine Operations Performance Standards, but as of 2017 ICAO now calls it EDTO (Extended Diversion Time Operations).
Not having a wet footprint means you will have the performance and fuel to make it to a specific airport; ETOPS is planning your route so you are always within a certain amount of time (usually 180 min) of an adequate airport at single-engine speed. Again, it's not required for private operators, but it is configurable within Foreflight if you want to adopt the practice.
Lastly, the Point of Safe Return (PSR) is where you cannot return to a diversion airport; you're committed to landing at your destination. Good to know, but as Q once told a Brosnan Bond, "Never let them see you bleed," and "Always have an escape plan."
Before entering the NAT
2024 marks a transition period for NAT Oceanic Clearances. Formerly, aircraft would pick up two clearances. One, as usual, is on the ground, and the second is for the oceanic portion en route before reaching an oceanic entry point (OEP). Depending on the OCA, you request a clearance (RCL) via Datalink or Voice (VHF or HF) 20-90 min prior to entry.
The NAT is moving to have the route portion of the oceanic clearance given while on the ground at your departure airport. Procedurally, not much has changed. The RCL process is still required; you're just not officially picking up a clearance anymore. They still call it an RCL because that's how avionics datalink boxes are coded. Long story short, this change allows ATC to clear aircraft as filed across the NAT from their departure airport.
For smaller aircraft, it's a moot point. Unless you have the range to overfly a coastal airport, you get your domestic and oceanic clearance all at once on the ground with domestic ATC.
For instance, if you're on the ground at CYYR, you request clearance from CYYR clearance delivery to BIRK. It may look like this:
N12345 Cleared to BIRK via
YYR - HOIST - 58°N050°W - 61°N040°W - 63°N030°W - EPENI - KFV -Direct
Climb and maintain FL280. Contact Departure on 120.4. Squwak 3333.
On the ground, it's an excellent time to verify a few things and record them on your Master Nav Log: ATIS, clearance, altimeter checks, LRNU accuracy, verifying waypoints (the flight plan, FMS, and Master Log all jive), block out time, and takeoff time.
Approaching the OEP
Before leaving domestic airspace, ATC will give you a primary and secondary frequency to contact the appropriate radio station. It's either HF or VHF - if you've advised them "negative HF." Continuing the above example, you would call Gander Radio and advise your ETA to the OEP, in this case, HOIST. Include your desired speed through the NAT (i.e., 270 knots or Mach 0.90). If your ETA to the OEP changes +-2 min, you need to update ATC. You'll get acknowledgment and instructions to call Gander over the OEP for your first position report.
In the NAT
You cross the OEP, start a timer, record your fuels and times on your master nav log, verify the course and distance to the next waypoint, and give the first position report. By adhering to the position report format phraseology, you will be doing everyone a favor:
"Gander Radio, N12345, Position on 125.5" - then wait.
After they respond, then launch into your schpeal: who you're talking to, your tailnumber, the waypoint you crossed, the time you crossed it, your flight level, the next waypoint and estimated time to cross, and finally, the following waypoint after that. Here is the exact wording:
"Gander Radio, N12345, HOIST at 1300z, FL280, Estimating 58N050W at 1400z, Next 61N040W."
They respond, "N12345, report over 58N050W on Gander Radio 125.5."
Ten minutes after you cross the OEP, you complete your first GNE check. This verifies you're on course. Active Navlog has an easy button feature for GNE checks. Alternatively, you can plot your position on your plotting chart using a non-steering nav source (2nd GPS if you have two) and mark up your Master Log.
Also, change your transponder code to 2000 ten minutes after entering the NAT. One exception to this rule is within the Reykjavik CTA. Here, they have radar surveillance coverage, so you can keep your squawk.
Listen to your given or expected radio station and emergency frequency 121.5. If you have another radio, you can add the air-to-air frequency, 123.45. As you continue, provide position reports and conduct altimeter checks every hour.
SLOP (6.4.3)
Now that everyone files purple needles and GPS is so accurate if two aircraft fly the same route, they will fly the same path within feet of each other. There is no variability between aircraft like there used to be flying on VOR or NDB navigation sources.
Strategic Lateral Offset Procedures (SLOP) re-introduces some variability to add a safety margin and reduce the risk of a mid-air. SLOP is considered standard operating procedure in the NAT, meaning if your aircraft is capable of lateral offsets, you should do so in the NAT.
You start SLOPing after crossing the OEP and stop before reaching the OXP (Oceanic Exit Point). SLOP is an offset right of course, from 0.1 nm up by 10ths to 2.0 nm. Pick your offset randomly (always to the right, always 2.0 nm or less). You do not need to advise anyone you are SLOPing.
Reykjavik and BODO OCA (off the coast of Norway) have an exception. Like the transponder code, since Reykjavik (and BODO) is a radar environment, you do not SLOP in their airspace.
Contingencies
Lost Communications (5.6)
The less communication equipment you have, the easier it is procedurally if you lose communications. Losing CPDLC, SATCOM, or HFs could limit your route and altitudes (See Blue Spruce Article). If you only have VHF to start with, it's pretty straightforward.
In general, use any available means to reach ATC. If you have a satellite phone, call them. If you can relay on 123.45 via another aircraft, do so. If all comms have failed, squawk 7600. If you are still in domestic airspace, that country's lost comms procedures take precedence.
If you lose communications outside oceanic airspace, you can continue your flight into the NAT, as you are not required to turn around. The PIC has the authority to make that decision. In that case, comply with the local lost comm procedures until the OEP and fly the last assigned clearance to the OEP.
Once inside the NAT, the rules change. In the NAT, maintain your currently cleared route, flight level, and speed until the OXP. Only change for safety reasons. If you were off course when comms were lost, rejoin before your flight plan's next fix.
Fly to the last fix (hold if necessary) and shoot an approach at the expected approach time if you have one or at the flight plan ETA. If the airspace has different lost comm procedures after the OXP, those will be primary.
Weather Deviations (11.4)
Ask and receive. Instead of a vector, be a little more specific. For example, "Gander Radio, N12345 request 10nm offset right for 50 miles due to weather." If you cannot communicate and get approval or need to take action before getting a clearance, there is a procedure for that:
If the deviation is less than 5 nm off course, stay at your assigned altitude and rejoin when able. Anytime you deviate more than 5 nm off course, apply an altitude offset. If deviating South, climb 300ft. If deviating North, descend 300ft—this is a simplification assuming you're flying East or West. Resume your correct altitude once you are back within 5 nm of your course. To repeat, if you have a clearance to deviate, this procedure is not necessary. If you lose comms or have to deviate for safety reasons, this is how you do so without a clearance.
Whenever you deviate without a clearance, communicate with other traffic by giving your position report of 123.45, turning on all lights, and watch out for others.
Emergencies (11.2)
The base case scenario is that you work out your diversion with ATC. However, if immediate action is necessary, either due to medical issues, loss of engine, or loss of pressurization, there are two sets of rules based on altitude. Most traffic is FL290 and above. In this block of airspace, the goal is to offset 5 nm from either your cleared course or the NAT tracks if they are in your vicinity. Then descend below FL290. This is why knowing where the tracks are located (and most of the traffic is), even if you are flying a random route.
Below FL290, it's the wild west. Once below FL290, you can Direct To your diversion point. Altitude-wise, offset 500ft from typical cruise altitudes (FL275, FL245, etc.).
Standard emergency procedures apply:
Turn the exterior lights on.
Squawk 7700.
Advise ATC.
Give Mayday (going to get wet) and Pan Pan (might get wet) calls if necessary.
Alert traffic in the area with calls on 121.5.
Watch for traffic.
Attachments
At the end of NAT Doc 007 are several important attachments. If you are investigated due to a GNE, Attachment 1 with your Master Navlog is what they will be looking for. Side note: You can learn from others' mistakes by reviewing Chapter 12, which is about guarding against common errors.
Some highlights include:
Not reprograming an FMS if given a re-clearance.
Flying the filed flight plan instead of the clearance.
Inserting an incorrect lat/long waypoint.
The North Atlantic Systems Planning Group (NAT SPG) periodically releases bulletins that update the list of most common errors. The Bulletins also address changes within the NAT.
Back to NAT Doc 007, altitude deviation and the wake turbulence forms are Attachments 2 and 3, respectively.
Attachment 4 is an oceanic checklist that walks you through some of the NAT procedures. A simplified NAT Oceanic Checklist, based on Attachment 4, is available for download here.
Master Navlog
A Master Navlog was referenced several times above. Hang tight; a full how-to write-up is in the works - both the paper version and the mentioned Foreflight Active Navlog.
Aviate
Look up some of the above references in NAT Doc 007.
Review the latest NAT OPS Bulletins.
Download a NAT Oceanic Checklist here.
