KSEA → KJFK Transcon (J70)

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📍 Route: KSEA → KJFK via J70⏱ ~10 minutes📊 8 steps🎓 Line Flying

The northern corridor: Seattle to New York via J70, a different routing into the same busy arrival.

What this scenario covers

Structurally this is the sibling of the J146 transcon, and running both is how the airway workflow becomes automatic rather than remembered. Different origin, different jet route, same skills — and the same CAMRN arrival at the end for comparison.

The northern routing crosses different terrain and different weather systems, which shows up in the flight plan as different waypoint density and, in real operations, different wind assumptions.

How it applies in flight ops

Dispatchers choose between northern and southern routings on winds and weather, not distance. The great-circle track is fixed; what varies is which jet route rides the best winds on the day, and the fuel difference between the choices is substantial.

For the crew, the practical consequence is that the filed route can differ from the usual one, and the box work has to follow the paperwork rather than the habit.

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Step-by-step: KSEA → KJFK Transcon (J70)

  1. On INIT, enter the route. Type KSEA/KJFK and press 1R.

    KSEA = Seattle-Tacoma, KJFK = New York Kennedy. The northbound great-circle route between them passes over Montana, the Dakotas, the Great Lakes, and Pennsylvania.

  2. Enter the flight number ASA20 (Alaska Airlines 20, a real SEA→JFK nonstop). Type ASA20 and press 3L.

    Alaska Airlines runs daily nonstop service SEA-JFK; ASA20 is the morning departure. The ICAO/IATA code split: ICAO is ASA (used in the FMS, flight plans, ATC); IATA is AS (used on tickets and airport screens).

  3. Enter cost index 70. Type 70 and press 5L.

    Different airlines pick different CI ranges for the same kind of route. Alaska runs leaner CIs than American on transcons — partly fleet (newer 737-9s with better fuel burn) and partly route economics. CI 70 still lands you within the published Mach 0.78-0.80 cruise envelope.

  4. Set cruise altitude FL370 (eastbound, odd FL). Type 370 and press 6L.

    FL370 is preferred eastbound on this route — the jet stream often runs westbound at this altitude, so eastbound flights ride the tailwind. Real flight data shows FL370/FL390 are the most common transcon eastbound levels.

  5. Press F-PLN. Then click LSK 1L on the KSEA row to open LAT REV.

    Same LAT REV gateway as the LAX scenario. The MCDU exposes <DEPARTURE only at the origin and ARRIVAL> only at the destination.

  6. On LAT REV FROM KSEA, press 1L for DEPARTURES. Pick runway 16L, then BANGR9, and INSERT* with 6R — leave the TRANS column alone this time.

    BANGR9's last common fix is BANGR, and no en-route transition is wanted here. Leaving the TRANS column empty is a real choice on a real unit, not a shortcut: a departure inserts its runway branch and common route, and the transition only if you ask for one. BANGR is not on J70, so the next step joins the airway at EPH. Note that the fixes before BANGR change with the runway — each runway end has its own branch out of Sea-Tac.

  7. BANGR is not on J70, so the airway cannot start there. Type EPH and press the LSK on the discontinuity line after BANGR: EPH takes that line and the discontinuity moves down below it. Clear it — press CLR, then the LSK beside the discontinuity. Then type J70, press the LSK on the EPH line to open AIRWAYS, enter JFK as TO (1R) and press INSERT* (6R).

    J70 is a real FAA jet route from the SEA VOR east to the NY area, terminating LGA-JFK. An airway can only be revised from a point that lies on it — otherwise AWY/WPT MISMATCH (FCOM DSC-22_20-30-10-15) — and J70 runs SEA, NORMY, BLUIT, EPH with no BANGR on it, so the plan reaches the airway at EPH first. A waypoint typed onto the flight plan leaves a discontinuity after it — the Airbus FCOM says a directly inserted waypoint "creates a discontinuity between the new waypoint and the previous one" — because the FMGS will not assume the route carries on from EPH. Clearing it with CLR is you telling it that it does. The AIRWAYS page then inserts the fixes from EPH to JFK.

  8. Click LSK on the KJFK row to open LAT REV, then 1R for ARRIVAL. Pick an approach, then CAMRN, then 6R to INSERT*.

    CAMRN is used by flights arriving from the northwest as well as the west — the merge point sits over central New Jersey. The approach you pick first is what tells the FMS which runway to build the last leg for. After insert, the FMS has the complete plan from the KSEA gate down the KJFK final.

What to take away

  • Same workflow as J146, different route — repetition is what makes it automatic.
  • Northern and southern routings are chosen on winds, not distance.
  • Program the route that was filed, not the route you flew last week.
  • Ending on the same arrival makes the comparison between the two directly visible.

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Background reading

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