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Wednesday
Sep082010

Holding

Holding is something that just about all travelers will inevitably encounter at some point.  I don't mean being put on hold when talking to airline customer service - I'm talking about "doing laps in the sky".

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Holding is a maneuver that pilots are required to be proficient in so that when an arrival into an airport or specific airspace is delayed they can keep their aircraft within a confined area of the sky while not actually going anywhere.

When a pilot is given hold instructions by air traffic control, they are given a fix (a point in the sky defined by highly tuned instruments), which side of the fix to conduct the hold on, which direction to turn when established in the hold, and altitude to hold at and what time to expect to receive further clearance.  Based on the aircraft's current position, the pilot (or some sophisticated auto-pilot systems) have to determine how to properly enter the hold and at what speed to conduct the hold at as holding speeds are highly regulated dependent on altitude.

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To put it lightly, essentially all the airplane is doing is making circles in the sky.  Let's look into why airplanes hold:

The most common reason for holding is an arrival delay.  If your destination airport has had inclement weather move into the airspace surrounding the airport, planes then require even more space between them on approach which causes plane to "stack" up.  Holding is used here to space out the aircraft so that the minimum distance between aircraft is maintained to a safe (and legal) distance.

If the weather happens to be a squall line quickly moving through, or a short thunderstorm (as is very typical at large airports like Atlanta, Tampa, Orlando, Ft. Lauderdale, Jacksonville, Charlotte, and Miami), arriving aircraft will be placed in a hold until the weather clears out.  Usually a summer thunderstorm can clear out in as little as 10-15 minutes.

A less typical reason for holding could be if there is a disable aircraft on the runway, or some sort of occurrence that temporarily shuts down a runway.  This is very rare.

The last one is the least common, and the vast majority of passengers will not only never experience this, but never even hear of it actually happening.  If an aircraft experiences some sort of mechanical issue while in-flight and a diversion or air-return (industry speak for returning to departure airport) is necessary, often the decision is made for the aircraft to hold to either dump fuel, or hold so long that most of the fuel is burned off.

Now stick with me here, this doesn't mean there is impending doom or an extremely dangerous situation is about to occur.

Usually it is something as minor as overheated brakes or the flight computer saying there is a disagreement somewhere in the system, or an anomaly in the engine instruments.  In these rare situations, the hold is used to burn fuel and for the pilots to discuss, brief, practice, and prepare what actions need to be taken.  This is also the time where pilots can call mechanics on the ground and/or mechanics at the aircraft manufacturing facility to discuss the issue.  Holding gives the pilots time to determine the safest course of action and to initiate those actions without being extremely pressured.

Holding is an operational necessity.  In some cases it is ATC driven, in some it is pilot driven.  In the end it is beneficial to all parties...and you can say you just played NASCAR in the sky.

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Monday
Sep062010

In-Flight Entertainment

Depending on which airline you fly you will see a wide variety of in-flight entertainment (IFE).  It could range from a deck of cards to full on audio/video on demand (AVOD).  Here's how airlines approach their IFE offerings.

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As with just about anything, it is all about cost and value to the airline.  

Low-Cost Carriers (LCC) are in the business of keeping low operating costs so that they can keep fares equally as low.  Installing a full AVOD system on a single aircraft runs a hefty price tag that can take years for that specific aircraft to recoup.  This is the main reason to keep IFE off an aircraft.

The lesser known cost for IFE is fuel consumption.  Carrying 100 IFE screens plus the processing units begins to add quite a bit of weight to an airplane.  In order to carry this extra weight, the plane must carry a proportionate amount of extra fuel, which raises costs across the fleet.  LCC's know that passengers prefer some sort of IFE, but in many cases the extra costs of IFE do not fit the business model that LCC's are trying to obtain.

Larger airlines that are not competing in the same fare realm as LCC's have a bit more room to wiggle on IFE, as well as airlines that fly long-haul flights.

These larger airlines (sometimes called Flag Carriers, or Legacy Carries, but not limited to those classifications) see more value in providing IFE to their passengers.

A long haul flight has seats that offer passengers some sort of personal viewing screen with a variety of recorded TV shows and recent movies.  More extensive IFE systems provide intra-aircraft multiplayer video games (think Trivia, not World of Warcraft or Halo) and meal ordering interfaces.

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The ability to watch live TV is a recent addition to many fleets around the world.  However, there is a restriction on this feature: when the aircraft is flying over the more desolate areas of the world the signal integrity is lost and renders this feature unusable.  This is due to the satellite coverage in the area being too weak to sustain the ability to stream live TV.

Here's a quick way to identify if your aircraft has live TV.  Look for the antenna in the photo below.  The hump on the top of the fuselage behind the wing is the live TV antenna:

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Last, we have what I consider is the best form of IFE: in-flight wireless internet.  Just about every US airline is adding it to their entire fleet.  Yes, it does cost, but the entertainment (and productivity!) gained is well worth it.  Some airlines have taken steps to block certain sites that may be inappropriate to view in the cabin environment, but generally speaking the system preforms near flawlessly.  It is worth mentioning, however, that the wireless signal's bandwidth is limited, so a passenger will experience a decrease in internet speed with an increase in users on the aircraft.

Enjoy your IFE! and please don't be this guy:

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Monday
Aug302010

Traveling with Infants

 @GvilleJen recently tweeted at me: “I heard some discussion on the radio of kid free flights or sections. Is that feasible? Would some pay extra?

That’s a great question, but before I dig into it let’s see how airlines typically handle children on flights.

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For reference, here are the policies and procedures at 4 of the major carriers in the US:

Delta

American Airlines

United

Continental

So from that sampling, we can see some air carriers require FAA approved infant seats, while other let infants under the age of 2 sit in the lap of an adult.  It is clearly stated at all airlines that infants are allowed on both domestic and international flights as long as an adult is accompanying them.  It is notable though that if an adult is traveling with 2 or more infants, a second seat or more must be purchased (usually at infant fare rates). 

It is pretty obvious and well known that infants can travel, there are just a few extra rules here and there to make sure the infants safety on the flight is the highest priority.

Where the debate comes in is the behavior of the infant.  We all know infants can be temperamental, but don’t file a loud baby under a “hungry” or “tired” fit just yet.

In the human body, there is a cavity on both sides of the back of the throat call the Eustachian tube.  This cavity connects the inner ear with the ambient air pressure (yes, the air pressure in your mouth is the same pressure as the ambient air pressure) outside your body in order to keep the enclosed inner ear cavity equalized.  When you increase in altitude (more specifically when the cabin altitude increases) air expands.  This is the slight popping sound you hear in your ears when you go through an altitude change.  The popping sound is your Eustachian tube automatically equalizing the pressure difference.  You don’t feel this in your mouth because it happens with no physical effect through your nasal cavity or just through opening your mouth.

In infants, as well as people with colds, deviated septums’, or any sort of condition that blocks sinus and nasal cavities, the Eustachian tube has a tough time regulating the pressure change and it can cause minor to severe pain in the passenger as the air expands inside the cavity.

This is when babies cry.

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When an adult has this problem, and if they are familiar with the Valsalva maneuver they can gently pinch their nose closed, and very, very gently blow air through their nose.  This manually opens the Eustachian tube and allows the pressure to level out and alleviate any discomfort.

An infant obviously cannot do this.  In fact, crying can actually help the infant in their quest for equal pressurization within its bodily cavities.  Opening your mouth wide open, as well as yawning, can trigger the Eustachian tube to equalize.  Feeding on a bottle or eating can also help the baby, but it is often the case that until the plane descends the infant will continue their noisy endeavor.

With that all laid out, there has been recent talk about making some flights child or infant free in an effort to keep cabins free of tearful infants.

While I certainly understand this sentiment, I am not exactly sure where I stand.  It really is not the baby’s fault the majority of the time.  It is going though an uncomfortable experience and I’m not sure airlines need to take an ageist standpoint and not allow infants to enjoy the same travel freedom of older humans.  And like it or not, the majority of us will one day be in that exact same position: traveling with a fussy infant, feeling helpless and hoping to dear god other passengers aren’t going to turn on them.

But on the other side of the coin, some hotels and even communities have age limits.

I’m sure there is a revenue potential for flights that are children free, and if there is a strong enough one then maybe the airlines should seize it.  And maybe if there are infant free flights there could be all infant flights as well?  Who knows, but for now, if the airlines are struggling so much, who are we to turn away any paying passenger?

Wednesday
Aug252010

Ground Delay Program

A ground delay program (GDP) is an initiative implemented by the FAA on a need basis to airports in the United States.  Essentially it is when an airport needs to reduce the frequency of arriving aircraft due to some sort of factor that is limiting the airports ability to operate at full capacity.  GDP's are most common during irregular weather at the destination airport or if the landing instruments at an airport have a service issue, but it can also be due to airport maintenance, runway closures, or service outages.  Let's dig in:

When inclement weather moves into the vicinity of an airport that reduces visibility at any level, the arrival capacity of an airport is reduced.  If an aircraft is on approach in a high visibility situation, they are given traffic advisories (about other aircraft in the sky near them) constantly, and are also given directions on how to avoid that traffic.  This is done by air traffic controllers telling a pilot to change their heading, speed, or altitude.  There are defined standards on how far apart, or spaced, the aircraft have to be while in the air.  If two aircraft are on approach to the same runway, the air traffic controller will space these aircraft appropriately, but will also give the pilots the ability to maintain a legal distance apart on their own authority.  This depends on many difference constraints, like how far apart two parallel runways are from each other, high-speed taxi-ways, number of runway exits, and so on.  Over the radio pilots are told to "maintain visual separation" during ideal visibility occurrences.

When the weather goes sour, obviously this can no longer happen.  The legal distance between aircraft on approach in bad weather increases.

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So essentially, when the weather is bad, aircraft must stay farther apart from each other and that typically means slowing down significantly.  Obviously, if the weather is good and they can arrive at the airport uninhibited, the airport can operate at a higher level of capacity than if the weather is bad.

This is where a GDP comes in.  When an airport starts to slow down, the FAA will issue a GDP that will affect all arriving flights.  Let's look at a theoretical example:

Tampa (TPA) airport has a GDP.  Heavy rain and low clouds have reduced visibility and arrival capacity is at 50%.  The FAA has issued a GDP to all arriving aircraft.  You are in Denver (DEN) on a non-stop flight to TPA.  Chances are, your DEN-TPA flight may have a delay, in DEN, because of the weather in Tampa.  The FAA will impose a departure delay on aircraft that are departing an airport to arrive into Tampa.  Depending on the amount of arrivals trying to get into Tampa, and the severity of the weather, the FAA will find a reasonable duration of delay to slow down arrivals.  So now you have a 15 minute ground delay in Denver.  After those 15 minutes have elapsed, if the FAA sees no change in the weather or arrivals into Tampa, that flight will be permitted to continue as planned.  If the weather gets worse, another delay may be issued.

This is where a lot of passengers can become frustrated.  The airline will initially tell them 15 minutes, but when the GDP is re-issued for even longer again and again, it can be a bit frustrating for both the airline and passenger.

The reasoning behind stopping aircraft on the ground is simple.  If they let the full capacity of aircraft arrive as they would under normal conditions, the aircraft may have to hold over the airport for long period of times, or even divert, which means a lot more fuel burned and wasted time.  Instead, it makes much more sense to keep the passengers on the ground and in the terminal until it is sure that the aircraft will be able to not have any in-air delays.

So that's that.  Please send me your questions!! I'm running a little short on ideas, so please fire away!

Friday
Aug202010

Airplane Geeks Podcast - UPDATED!

Follow up!

The @airplanegeeks podcast is up!  Stream it from here.

I do have a small aside though to the podcast.  The reason why the airline I work for was not revealed was because I did not want any of opinions that I expressed to be confused as a reflection of my company.  The opinions I expressed on the podcast are mine, and solely mine.  Thats it guys.

Let me know what you think!

P.S. - I added a "Donate" button on the sidebar.  It isn't there to make money, but rather to help offset the hosting charges.  Have at it!

_______________________________

So this isn't really a real post, but a pretty neat update on the aviation side of things.  Over the weekend I will be a guest on the Airplane Geeks Podcast.  The Airplane Geeks (@maxflight, @jetwhine, @danwebbage, @DMVanderhoof) are a group of aviation buff's who have a podcast on all things aviation.  Every week they have a different guest on the podcast and I will be recording with them this weekend for an upcoming show.

If you guys are podcast fans like I am, be sure to either subscribe to their podcast through iTunes or visit their website to stream episodes.  I'll be sure to post an update when the podcast goes live!

 

P.S. Just so I can nudge him along a little more, I've got an upcoming guest post from an old instructor of mine who is now a pilot for a regional carrier.  He is going to bring a little more insight to the blog from a more technical viewpoint on what happens in the cockpit.  Send me your questions so I can forward them to him!