Changes of Gauge

Delta flight 160, Denver to Amsterdam, landed today (December 1, 2014) in Amsterdam with no Denver passengers on board. This is not uncommon: it also happened with DL160 on November 13.

The explanation starts with a "change of gauge," a term rooted in railroads.

Track gauge is the distance between the inner faces of the two rails. This year I've traveled on three different gauges:

Standard (4 ft 8 1/2 in, 1,435 mm): in England, USA, Greece, Japan
Narrow (3 ft 6 in, 1,067 mm): Japan
Wide (5 ft 3 in, 1,600 mm): Ireland (North and South)

Usually, when the gauge changes, you get off one train and walk to another train with a different gauge.

You arrive at Japan's Kagoshima-chuo station by bullet train (Shinkansen) on standard-gauge track (pictured at the top of this post). 

You then head downstairs to continue your journey on the narrow-gauge regional network. Most lines in Japan are narrow gauge.

The International Air Transport Association's passenger glossary of terms defines "change of gauge" as:

[A] flight which is published by an airline as a direct flight between two points but which involves one or more changes of aircraft en route. Typically this would involve a short-haul service feeding to or continuing from a long-haul flight.  

For example, DL160 from Denver to Amsterdam has a change of gauge in Minneapolis/St. Paul:

DEN/MSP: single-aisle Boeing MD90
MSP/AMS: two-aisle Airbus A330-300

Gauge-change flights list along with nonstops near the top of flight searches. Confused customers may think:

They've booked a nonstop,
Or, one plane will carry them from Denver to Amsterdam,
Or, it's a guaranteed connection.

None of these expectations matches reality.

Yesterday (November 30), the busiest travel day of the year, Denver had poor visibility. The first DL160 had not yet departed DEN when the second DL160 departed MSP for AMS.

Note: DEN time (Mountain) is one hour behind MSP (Central)

It is usually not in the best interests of the majority of passengers or the airline to hold a flight for a delayed inbound flight.

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Airlines use "change of gauge" to mask a marketing ploy. For railroads, different gauges are a reality. 

Railroads have gone to extraordinary lengths to accommodate different gauges.

One option is to lay three, rather than two rails. The outer rails are standard gauge, while the inner and one outer rail support narrow-gauge traffic. The 33.5 mile (54 km) Seikan undersea tunnel connects the islands of Honshu and Hokkaido with this system. 

Gauge-change trains have wheels that adjust as the train moves from one gauge to another. Several countries, including Spain, have gauge-change trains. 

Another option is to lift each passenger car off its wheelsets (bogies) and deposit it on wheelsets with a different gauge. The Moscow (Russia) to Pyongyang (North Korea) sleeper train switches wheelsets at the border. 

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I try to regard a change of gauge or a missed connection as an adventure. I'd make a detour to experience a gauge-change train or a switch of wheelsets.

I can choose to make the unexpected or unusual the best part of a journey.

Wide gauge, Galway, Ireland

Notes: 

Delta 160 from DEN finally arrived in MSP at 12:21 a.m., December 1, over 10 hours behind schedule. Delta 160 arrived AMS at 5:57 a.m., December 1, over 35 minutes ahead of schedule.

Had I been booked on that flight in DEN, I probably would have asked to be re-booked to fly the next day (Monday December 1) from DEN. I find airline agents are open to such requests.

The same misconnect occurred November 13, but the DEN delay was much shorter. The plane from DEN was probably on the ground at MSP when DL160 took off for AMS without the DEN passengers. This served the greater good.