RTE Airway Entry & the "INVALID ENTRY" Decoder

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📍 Route: KLAX → LAX → LAS (via J146)⏱ ~5 minutes📊 10 steps🎓 Flight Plans & Routing

The error message every 737 pilot meets on the RTE page — INVALID ENTRY — has three quite different things to tell you, and it will not say which.

What this scenario covers

Airways are entered on RTE as a via/to pair: the airway in the VIA column, the point where you leave it in the TO column. The VIA line has one refusal message for three faults — an airway that does not contain the waypoint the route is at before it, an airway the navigation database does not hold, and an airway that does not contain the waypoint you asked it to end at. All three come back INVALID ENTRY.

The first catches most people, because the airway is real: no airway contains an airport, so an airway typed straight after the origin is refused. The route has to reach the airway first — a TO waypoint entered with no airway above it becomes a DIRECT leg, and the airway is then joined from there.

Reading past the message is the skill, because the box will not do it for you. Check the airway is real and current, check it contains the fix you are coming from, then check the exit fix is on it. Retyping the same thing harder fixes none of them.

NOT IN DATA BASE is a different message on the same unit and it is worth knowing where it lives: an identifier the FMC has never heard of — a company route on RTE 1, or a waypoint or navaid you look up on REF NAV DATA. It is a statement about the database; INVALID ENTRY is a statement about the entry.

How it applies in flight ops

Routes are loaded from the OFP under time pressure, and this message is the most common friction point. A crew fluent in what it can mean resolves it in seconds; one that is not ends up deleting and rebuilding good route segments.

Occasionally the message is right and the plan is wrong — an out-of-cycle navigation database, or a route filed against an airway structure that has changed. That is worth noticing before departure rather than in the climb.

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The CDU checks every entry as you make it, and tells you when an entry was accepted but wrong.

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Step-by-step: RTE Airway Entry & the "INVALID ENTRY" Decoder

Set up a route to work with. Press the RTE key, then type KLAX into the scratchpad and press 1L to enter the ORIGIN.
KLAX is Los Angeles. The RTE page is where the route begins — origin on the left, destination on the right. The FMC needs both before it can build the enroute legs.
Type KJFK and press 1R to enter the DEST (destination).
KJFK is New York JFK. With origin and destination set, the FMC has the two endpoints — but no path between them yet. You build that path on the second RTE page using airways.
Open the second RTE page, where airways are entered on the real 737. Press 6L (<RTE 2).
On the real Boeing 737 the route is built on the RTE page using VIA/TO columns — the airway goes under VIA (left), the exit waypoint under TO (right). The LEGS page only shows the expanded leg sequence; it does not accept airway entries.
Start with the airway you were actually cleared on. Type J146 and press 1L to put it in the VIA column. The CDU refuses it with INVALID ENTRY — even though J146 is a real airway.
The VIA column has one refusal message and three reasons for it, and this is the one pilots meet first: an airway must contain the waypoint the route is at before it. Here that is the origin, KLAX, and no airway contains an airport. J146 begins at the LAX VOR, not at Los Angeles International. The FCOM lists it as the first invalid VIA entry: "airways and company routes which do not contain the TO waypoint of the previous line" (§11.40.17).
Give the route somewhere to join J146 from. Type LAX (the VOR where J146 begins) and press 1R, the TO column of the first line.
A waypoint entered in the TO column with no airway above it becomes a DIRECT leg. The FCOM puts it this way: DIRECT "is normally entered as a result of entering a TO waypoint first" (§11.40.18). KLAX, then DIRECT to LAX, is the leg that reaches the airway, so everything after it can be built along J146, starting on line 2.
Now the second reason for the same message. Type J999 (an airway that doesn't exist) and press 2L, the VIA column of the line below DIRECT. The CDU rejects it with INVALID ENTRY.
This time the FMC has no airway with that name in the current AIRAC cycle. Almost always it is a typo (J999 for J99), an airway outside your database coverage, or a victor/jet-route prefix mistake (V for J). Note what the box did NOT say. NOT IN DATA BASE is this FMC's message for an unknown IDENTIFIER — a company route on RTE 1, or a waypoint you look up on REF NAV DATA — and the VIA line does not use it.
The real airway is J146, and now it has a place to start. You don't need to clear the message — just type J146 (it replaces the error) and press 2L to stage it in the VIA column.
The same airway the CDU refused a minute ago, accepted now: the line above ends at LAX, and LAX is on J146. J146 is a real high-altitude jet route across the western US. Once staged it is a pending change — the title reads MOD — and the CDU waits for the TO waypoint that says how far along it you'll travel.
And the third reason. The waypoint where you leave the airway must actually lie on it. Type DEN (Denver — not on J146) and press 2R, the TO column. The CDU rejects it with INVALID ENTRY again.
Same message, third fault: the TO waypoint exists, but it is not one of the fixes that define this airway (FCOM §11.40.17). That is why INVALID ENTRY on this page is a question rather than an answer: check the airway is real, check it contains the fix you are coming from, then check the exit is on it. Here the fix is to pick a waypoint from the airway's own sequence; your flight plan names the exit fix dispatch filed.
LAS (Las Vegas) is on J146. Type LAS (it replaces the error) and press 2R to set it as the airway exit in the TO column.
LAS is an early fix on J146, so the FMC will follow the airway from LAX as far as LAS. With the DIRECT leg and the airway (VIA J146, TO LAS) staged, the route shows MOD and the EXEC prompt lights so you can commit the change.
Press 6R to EXEC the staged route. The pending entries become the active flight plan.
EXEC commits any pending route change on the Boeing FMC — nothing you stage takes effect until you press it (the real aircraft also has a dedicated EXEC key). That's the whole RTE airway workflow, and you now know all three things INVALID ENTRY can mean on the VIA/TO lines — and where NOT IN DATA BASE turns up instead.

What to take away

INVALID ENTRY on VIA: the airway does not contain the fix before it, is not in the database, OR does not contain your exit fix.
No airway contains an airport — join it with a DIRECT to a fix that is on it.
The message does not distinguish the three — check the airway, then where you join it, then where you leave it.
NOT IN DATA BASE is for an unknown identifier: a company route, a waypoint, a navaid.
The via/to pair is the unit of entry — both halves must agree.
Persistent rejections can mean a stale database or a bad flight plan, not a typo.

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