Prefer Off vs Avoid: When to Use Each

Two Commands, Completely Different Mechanics

Every PBS bid has two types of negative preferences: Prefer Off and Avoid Pairings. Most pilots treat them as interchangeable. "I don't want to work that day" or "I don't want that kind of trip." But they do very different things to the PBS engine, and using the wrong one in the wrong situation is the most common cause of bad awards.

Prefer Off removes dates from your availability. It tells PBS: "Try to keep me off the schedule on these days." If PBS can honor it, those days stay clear. If it can't, it denies the Prefer Off one date at a time (right to left) until it can build your line.

Avoid Pairings removes trips from the pool. Permanently. It tells PBS: "Delete every pairing that matches this filter." Those trips are gone. PBS cannot use them to build your line, even if it needs them. If too many trips are removed, PBS can't build a legal schedule. That's when things break.

The difference: Prefer Off is reversible. Avoid is not.

How Prefer Off Works

Prefer Off has five selection modes:

Dates in a list are processed left to right by priority. If PBS can't honor all of them, it denies from the right first. Your last-listed date goes before your first. Put your most important day off first.

The Two Modifiers

All or Nothing honors every date or ignores the entire Prefer Off. PBS continues processing the same bid group either way. Essential for commuters who need contiguous days off. A single isolated day off at base is worthless if you can't commute home.

Prefer Off Dec 24, Dec 25 All or Nothing

ESN (Else Start Next Bid Group) tells PBS: if this Prefer Off can't be honored, abandon the entire bid group and move to the next one. Use this on the one preference that makes the whole group worth having.

Prefer Off Weekends Else Start Next Bid Group

Time Ranges

You can request specific hours off, not just full days:

Prefer Off Between Dec 24 18:00 And Dec 26 08:00

This tells PBS to keep you off from Christmas Eve evening through the morning of the 26th. You're available during the daytime on both days. Useful when you want the evening and morning with family but will fly during the day.

What Happens in Denial Mode

When PBS enters denial mode, Prefer Off dates are denied one at a time, right to left. Your last-listed date goes first, then the second-to-last, and so on. Date ordering matters. Put your highest-priority date first in the list.

If a Prefer Off has ESN and gets denied, PBS doesn't strip dates one by one. It abandons the entire bid group immediately.

How Avoid Works

Avoid Pairings uses the same 45+ filter conditions as Award Pairings (PWA Section 23 / MOU #1). Common examples:

Avoid Pairings If Any Layover In JFK
Avoid Pairings If Pairing Length < 3
Avoid Pairings If Any Redeye
Avoid Pairings If Average Daily Credit < 5:15
Avoid Pairings If Carry-Out > 0

Every Avoid permanently deletes matching pairings from your pool. The trips aren't deprioritized. They're gone. PBS cannot use them even in denial mode.

In denial mode, an Avoid is denied completely, all at once, not one filter at a time. If your "Avoid Pairings If Pairing Length < 3" is denied, every 1-day and 2-day trip floods back into your pool simultaneously.

The Pool Math

This is where most pilots get in trouble. Every Avoid shrinks the pool:

• Avoid 1-day trips removes 15-30% of trips in most categories
• Avoid redeyes removes another 10-20%
• Avoid specific layover cities removes 5-15% each
• Avoid low daily credit could remove 20-40%

Stack four or five Avoids and you've potentially eliminated 60-80% of available pairings. PBS has to build your entire line from whatever's left. If that's not enough trips to reach the LCW minimum, you get "No pairings available" in your Reasons Report.

When to Use Which

Use Prefer Off When:

• You want specific calendar days off. Prefer Off is designed for this. Avoid filters by trip characteristics, not dates.
• You want flexibility. Prefer Off is reversible in denial mode (stripped one date at a time). Avoid is all-or-nothing.
• You're junior. Junior pilots have smaller pools to begin with. Every Avoid makes it worse. Prefer Off keeps the safety net.
• You're bidding around holidays. Per ALPA guidance: use Prefer Off for holidays, not just Award-based strategies, because coverage can override Awards but Prefer Off still signals your intent.
• You want a minimum credit line. The classic strategy: Prefer Off [entire month in priority order] forces PBS to stop adding pairings once you're inside the LCW. This only works with Prefer Off, not Avoid.

Use Avoid When:

• There's a trip characteristic you truly cannot fly. Redeyes that destroy your health. Specific airports your doctor told you to stay away from. Carry-out trips that conflict with a commitment the following month.
• You have strong seniority. Senior pilots have larger pools. More trips remain after filtering. An Avoid that's safe at the 20th percentile might be catastrophic at the 80th.
• You want to prevent a specific kind of trip. Prefer Off can't filter by trip characteristics. It only blocks dates. If you want "no 1-day trips" or "no JFK layovers," Avoid is the only tool.
• You're using CSSN (Clear Schedule and Start Next Bid Group). With CSSN, PBS won't deny your Avoids. It jumps to the next group instead. This makes Avoids safer within a CSSN-protected group because you have a clean fallback.

The Seniority Decision Matrix

Your position in the category changes which command is safer:

Practical Examples

Holiday Bidding

Good — Prefer Off approach:

Prefer Off Dec 24, Dec 25, Dec 26
Award Pairings If Pairing Length 3 Days
Award Pairings If Pairing Length 4 Days
Award Pairings

PBS tries to keep the holiday clear. If it can't honor all three days, it drops Dec 26 first (rightmost). Your line still gets built.

Risky — Avoid approach:

Avoid Pairings If Depart On Dec 24
Avoid Pairings If Depart On Dec 25
Award Pairings

This permanently removes every trip departing on the 24th or 25th. If those trips were the only ones that fit your LCW, PBS has nothing to build with.

The Commuter

Smart commuter bid:

Prefer Off Dec 24, Dec 25 All or Nothing
Award Pairings If Work Start Station LAX
Award Pairings If Work End Station LAX
Award Pairings If Check Out Time Between 06:00 and 15:00
Award Pairings

All or Nothing ensures you're not stranded at base with a single useless day off. Work Start/End Station keeps trips anchored to your commute city.

Minimum Credit Strategy

Set Condition Minimum Credit
Prefer Off [days you want off]
Avoid Pairings If Average Daily Credit < 5:15
Award Pairings If Pairing Length 4 Days Limit 3
Award Pairings If Pairing Length 3 Days Limit 2
Prefer Off [entire month in priority order]
Clear Schedule and Start Next Bid Group

Notice: only one Avoid (low daily credit, a real dealbreaker). Everything else is Prefer Off. The month-long Prefer Off at the end tells PBS to stop adding trips once you're inside the LCW. This is the safest minimum credit construction.

The Bid Order Rule

Regardless of which command you use, they must appear in the right order within your bid group:

Prefer Off → Avoid → Set Condition → Award

Negative preferences (Prefer Off, Avoid) filter the pool BEFORE Award statements draw from it. If you put Awards above Avoids, PBS tries to award trips before the pool is filtered. The results are unpredictable.

What Comes Next

How PBS Bidding Works covers the full processing engine: what happens to your bid after you submit it, including denial mode, shuffling, and SLG.

How to Read Your PBS Reasons Report walks through every status code that tells you whether your Prefer Off and Avoid choices worked or broke.