When ya gotta go, ya gotta pay.

Dublin-based discount airline Ryanair (RYAAY) may charge passengers one pound (about $1.40) to use the lavatory when in flight - or, as they say on the far side of the pond, folks may have “to spend a pound to spend a penny.” ("Spend a penny" is British slang for, well, never mind.)

Fees for formerly free services or conveniences are part of an effort by airlines worldwide to boost revenue. Fees for checked baggage began to show up last year as fuel prices soared. Many airlines quickly added charges for snacks, pillows and blankets to offset empty seats.

US carriers have been hit hard. Southwest (LUV) is the only major carrier to report a profit last year. Airlines reporting loses for 2008 include Alaska (ALK), Continental (CAL), US Airways (LCC), American (AMR), Delta (DAL), United (UAUA) and JetBlue (JBLU).

Airlines are scrambling for passengers. JetBlue now lets customers who lose their job get a full refund for up to 9 reservations, if certain conditions are met.

The International Air Transport Association, a trade group, expects the airline industry to lose about $2.5 billion in 2009, or about half of what the group’s 230 members lost in 2008.

Dublin-based Ryanair already charges about $42 for checking a bag, $14 to buy a ticket with a debit or credit card, $84 to check sports or music equipment and $70 to change a flight.

Such fees make the airline very popular with passengers. Readers responding to a tongue-in-cheek survey by the London Telegraph said they expected Ryanair to charge next for reclining seats and air-sickness bags.

Great idea! What charges have airlines missed? Maybe:
 

• Smiling flight attendant: $10
  
  
• Abusive flight attendant with whip and the skill to use it, $25
  
  
• Snacks, $10
  
  
• Edible snacks, $20
  
  
• Seatbelt, $10
  
  
• Rope in lieu of seatbelt, $5
  
  
• Airtight window, $15
  
  
• Cork for screaming kid across the aisle, $50
  

Of course, there’s the simple solution: Emulate Southwest Airlines.

The discount carrier operates with all the grandeur of a bus company and zips past its competitors to consistent profitability. Southwest’s down-home philosophy: one size fits all.
But it provides good service while keeping costs low - what a concept.

This suggests that top management at Ryanair must be -- ahem -- a little intellectually constipated.