Why both hardcore A320 and B738 fans hate me!

I loathe Airbus versus Boeing debates. Yes, I hate it with a passion. In online forums, by the time you get to a dozen replies, the hardcore fans (ie: blind believers) start hijacking the topic with marketing gimmicks and junk and both sides try to drown out the facts (because it simply doesn't suit them).

One day, I decided, I had enough! I did a fuel burn comparison between the 737-800(w) and the A320-200 (Both CFM56-5Bs and IAE V2500-A5s). When I post them on 737 vs 320 debates, the comparison would either kill the discussion (because the fanatics have no room to wriggle), or it ends up being a slag-fest of outrageous claims.

Let's look at the comparisons:

Max Capacity Fuel Burn:

Simple, A320 wins on the trip burn, but 737-800 can get more seats in so the fuel burn per seat is lower in this aspect.

180 seat and 165 seat capacity or load fuel burn:

Once you go above 500NM, the IAE powered 320s, win. The CFM powered 320s, starts to win above 600NM.

100 seat load fuel burn

This shows that whilst the A320 would win over 600NM (again), its heavier airframe does penalize fuel burn for the shorter trips.

20-ton payload fuel burn

I did this because airlines do not solely look at cost per seat. Cargo, is an important source of revenue on passenger flights. So a Payload based fuel burn comparison gives an idea on how much profit one can make.

Notice that the IAE powered A320s, now start to win at a mere 300NM trips, whilst the CFM powered ones (again), need 600NM to start getting the edge on the 737-800W.

Time Comparison

Self explanatory

SO WHICH ONE IS BETTER?

Answer: IT DEPENDS.

If I have an airline operations where my routes are predominantly 350NM or less, in terms of fuel burn alone, I'd be called a fool to start chosing the A320 with CFM56s. If my routes are predominantly over 500NM, again, I'd be called a fool if I choose the 737-800W.

But, we know that it is not that simple. After all, we still see 737-800Ws being churned out from Seattle, and the A320 with CFM engines are still selling well.

If fuel is cheap, by all means, go for the 737-800. If fuel is expensive, the A320 with IAEs do look attractive. The good news is, fuel price is an important factor, but is not the only important factor to consider. Maintenance cost is another major issue. The CFM56s are dirt cheap to maintain in comparison to the IAE V2500s albeit more reliable and durable, but the airframe maintenance costs are very similar between the A320 and the 738. This is also reportedly true for the price of the engines.

Of course, there are a myriad of other factors to consider too. At the end of the day, which one has the edge, could be determined by something as simple as who sneezed at the wrong time during the price negotiations!

Kill the drag!

A Taliban drag queen being escorted by Afghan forces to face justice!

No, the drag queen is just a joke, I'm talking about "winglets" and why is there such a variety?

In crew talk here, a winglet refer to two things.

1. That wingtip thingy-magic that's supposed to make our flights cheaper by saving fuel.

2. Male F/As that act like drag queens (ever seen one with his arms out to his sides and both hands pointing upwards when greeting you?).

It's no brainer, I'm not talking about killing male F/As that act like drag queens (even though I don't want to be locked up in a hotel room with one). I'm talking about our basic need to save fuel!

I'm not going to talk about the history of the aerospace engineers conjuring up funny equations. I'm also going to talk on the business side. The truth in the history of the winglet that we know today, is that no one cared about drag reduction wingtip devices until Iran decided to get people to think about fuel savings (if there's one pariah we need to thank with today's improved fuel efficiency technology, we reluctantly have to thank the Ayatollah).

Let's start with a little aerodynamics though. We don't put these things up just because they look pretty.

Where does the drag come from?

Lift for an aircraft is created because the lower side of the wing has higher pressure than the top. All sounds nice and dandy, but what about on the wingtip where both the upper and lower sides meet.

Tip Vortex by Citizenhom (Creative Commons)

Air is like a fluid, it always wants to move from high pressure to low pressure. So, the high pressure air near the wingtip, spills over to the lower pressure air, hence air from the lower side moves to the upper side of the wing, and as it moves forward, it creates a vortex behind it.

This creates drag... the vortex sucks its energy from the airplane, causing it to be less efficient.

Photo by NASA

As planes go higher and faster, this drag, increases. Scientists and businessmen in the industry agree to do one thing... 

KILL THE DRAG

Thanks to rising fuel prices since Iran fell, the urge to save fuel consumption continue. The old days of flying fast is long gone as it takes a lot of energy to punch an airplane through the air at high speed. Flying slower reduces the energy needed, hence lower fuel consumption. Unfortunately, lower speed means you've reduced the aircraft's total drag, but increasing the percentage of wing-tip vortex drag out of the total drag. You can fight this drag by various means: 1. Increase the wing span whilst maintaining the aspect ratio. This reduces the lift-induced drag (including the wingtip vortices), but the question is, just how wide do you want the wingspan to be? There's a limit to this, both economic and structural constraints. 2. Optimize wing loading distribution by concentrating the lift nearer the body of the aircraft, so that you can afford minimum pressure differential at the wingtip, but this has manufacturing and maintenance complexities. 3. Put up a barrier!

Wingtip devices, are method number 3.

1. Containment method.

Ever seen a downward facing wingtip? This is made to contain the air from spilling over to the side. This is effective for slow speed aircraft, but for high-speed aircraft such as commercial jet, most of the spillover happens behind the wing, and the vortices are much much larger than the downward wingtip.

2. Wing-tip Fence like you find on the A300-600, A310-300, A32X family (except A320-100) and A380

Photo by: Joe Roland/V2 Photography

• Method: Putting a small vertical fin at the wingtip, reduces the vortex effect. The small size focuses on the small radius high speed wingtip vortex which is the major component of wingtip vortex drag.
• Benefits: Drag reduction at low weight penalty therefore still suitable for short flights. Small size does not affect crosswind landing/take off limits. Minimum interference drag too!
• Problems: Not effective for speeds significantly higher than wing's optimum speed as the vortex size will render the fence useless. However, the Airbus use supercritical wings which makes its optimum speed on the higher end of the operating envelope.

3. The Standard Winglet like you find on the 747-400, A330 and 340

Photo by: Joe Roland/V2 Photography

• Method: Adds aspect ratio without significantly adding the wingspan. Just add the span and hammer the tips upwards (sarcasm). The cant angle (angle of the wingtip going up) and the toe angle differs from aircraft to aircraft. The rotating vortex going up is stopped by the winglet, the cant angle will capture this to push the wing up, and the toe angle pushes the flow backwards as a form of, flow induced thrust. As long as the "induced thrust" is higher than the remaining induced drag, this method can be very effective.
• Benefits: Big boost in aerodynamic efficiency and increases high altitude cruise stall margin. Enables the aircraft to fly higher.
• Problems: Additional weight is something to watch out for. Interference drag exists (nothing stopping the lower airflow spilling over), and the boundary layer drag hitting a sharp angle will create another vortex.

4. Winglet-Fillet Combo of the MD-11

• Method: Standard winglet added with a lower wingtip fence below the winglet.
• Benefits: As per standard winglet but with lower interference drag.
• Problems: I'm never clear on the penalties caused by this, but many suspect it was never really perfected as it's sole major user in the past, the MD-11, didn't really sell as well as we all expected (but that's another story).

5. Blended Winglet a la 737NG and soon the 320NEO

Photo by: Joe Roland/V2 Photography

• Method: Same as the standard winglet but is not "stabbed into" the wing, instead, it is curved to eliminate the interference and boundary layer drag. This leaves literally no drag penalties for high speed cruise that dogged the standard winglet and winglet-fillet combo. And oh, yes, it looks good (to the certain extent that it tempted Airbus)
• Benefits: Self-described in the method.
• Problems: Weight is an obvious one, especially when deployed on "small" aircraft such as the 737NG. Crosswind limits are affected too, because you're basically adding two big sails on the end of the wings. The curve also require wingspan increases before you even go to the winglet. This eats gate space.

6. Raked Wingtips a la 767-400, 777-200LR/-300ER, 787-8

There's a pair of raked wingtip somewhere in this photo
(photo by: Joe Roland/V2 Photography)

Designers have long thought on how to reduce drag for more than the 3.5 % (wingtip fence and standard winglet), 3.75% (the winglet fillet combo) and 4.5% of the blended winglet. (Note. these numbers are just rough and I forgot where the numbers came from!) They broke the 5% barrier with the raked wingtips.

• Method: Higher sweep angle at the wingtip than the rest of the wing.
• Benefits: Increases aspect ratio & reduce lift induced drag, by spreading the wingtip longer with the higher sweep angle. This has the same effecft as the winglet and blended winglet without reducing the crosswind landing and take off limits. It is also surprisingly, not heavy!
• Problems: Gobbles down gatespace like no other wingtip device because it really does increase the wingspan, this is why the 787-3 was designed with a winglet and not a raked wingtip.

But that's not all! Don't forget the other ideas:

7. Non-planar wingtip

This is a collection of various ideas. The A350XWB will use this by combining the blended winglet and raked wingtip idea. Another non-planar wingtip is the spiroid winglet. Aviation Partners (who designed the blended winglet for the 737NG) is researching this on some bizjets, and have reported reduction in fuel consumption by over 10%, however, it does look strange!

8. The MAX's hybrid wingtip

Lucky that looks don't always match aerodynamics
(image from Boeing)

How do you expand a wingtip fence, to become some form of a blended winglet without the weight, but also reduce the interference and boundary layer drag common to the winglet and winglet-fillet combo? Simple, you get a winglet-fillet combo, and hammer it to pieces till it's all bent with no sharp corners! The improved performance over the blended winglet, is around 1.5%, and you don't get the gate space growth associated with the raked wingtip. The only problem is, it looks ugly!

ENOUGH WITH AERODYNAMICS! What's in it for the passengers?

Let's start with what you don't want... 

• Additional advertising space on the winglets (not available on raked wingtip). 
• Lower costs. Let's admit it, fuel is just too damn expensive now, so reducing fuel burn by drag reduction, is making flights cheaper for us.

BUYER BEWARE! You may not get the results you expected!

I want to focus on the battle of the millenium, the A320 vs 737 war, which the upcoming battle is going to be the NEO and the MAX. I'm well aware of the touted benefits of the Blended Winglet. However the marketing material is so effective that we often forget the reality. We're now seeing 737NGs with those winglets flying short routes.

Here's the bad news from the realists. Short routes with winglets cost more than without! On short routes, climb becomes a greater portion of the total flying time, so does flight time spent at low levels, and it is in these conditions that the winglet's weight can end up as a penalty (climb), or its parasitic drag due to increased aircraft surface area (low level).

I looked at the trip performance numbers of the 737NG with and without winglet. Anything 300NM or less, you'd be stupid using the winglet. Above 600NM, the benefits start to come in. The Airbus A320 however, isn't a loser against the 737NG with the blended winglet, but the comparison between the two, does accentuate one thing: WEIGHT RULES AT SHORT DISTANCES! The A320's heavier airframe lose out on flights below 300NM, but beyond 600NM, it's all up to the aerodynamics and engines, and even with a mere wingtip fence and it's amazing supercritical wings, the 320 (with the IAE V2500-A5s or CFM56-5Bs) beats the 737NG on a per ton payload basis, consistently.

Before adding winglets to your 737NG or A320, consider
the composition of the mission profile
(photo by: Joe Roland/V2 Photography)

Airlines must therefore, when faced with the option to have wingtip devices, take a careful look. How long is their average mission profile? Are the rotation segregable or not between the ultra short-haul and the rest of the aircraft type operations? Does the added weight of the wingtip devices affect the landing weight limitations based on the mission profile to the extent of penalizing payload or not?

The questions to answer goes on and on as fuel prices go up and up.

However, operations department may be churning operating cost numbers behind the scenes, but the airline as a whole must not forget that the profit consists of two components: Revenue and Cost. Costs can be as low as possible, but revenue is also important. That is why, depending on the mission profile, getting a bigger and more aerodynamically efficient wingtip device for your aircraft, may not always be the answer. Operations department must be more commercially aware.

But why am I talking about this when the new aircraft with options to have a wingtip device or not is only the 737NG? Simple, the A320 and its upcoming NEO will have the option of a wingtip fence or a "Sharklet"...

(image from Airbus)

Latest addition to Indonesia Air Asia spotted: PK-AXW

Indonesia Air Asia's 22nd A320 will arrive in Jakarta soon. The latest, PK-AXW with msn 5137 was recently spotted making its first flight on 24th April 2012:

First Flight of Indonesia Air Asia's 22nd A320 (to be 19th in current ops)

Indonesia Air Asia currently operates 18 A320s. Towards the end of 2011, 3 new A320s on lease were sent to Malaysia Air Asia (PK-AXN, AXO, AXQ) in exchange for 4 "old" A320s (PK-AXR, AXS, AXT, AXU) from the latter, sold to Indonesia Air Asia, to comply with the regulations in force beginning 1st January 2012, where airlines must have 5 owned aircraft and at least 5 more leased aircraft. But don't worry, the oldest one is from as late as 2006.


(Thanks to @arifmuharram for the heads up!)

737MAX announcement: Has Boeing and Airbus run out of ideas?

Boeing has just announced the new design features of the upcoming 737MAX. While I wasn't expecting much, other than the focus being on the new engines and the challenges surrounding putting a larger fan on an aircraft with its short and stumpy landing gear, but I ended up shaking my head in disbelief of the disappointing kind.

New rendering of the 737Max (image from Boeing)

I was unimpressed when Airbus released the NEO, with it's so-called Sharklets. To me, it's nothing but a redesigned blended winglet like Aviation Partner's blended winglet for the 737NG. Yes, the new engine sounds good, but the sharklets? Seriously, I thought Airbus had run out of new ideas decided to copy Boeing... that is, until today's 737MAX announcement.

A320NEO... and we thought Airbus gave up and decided to copy Boeing!
(image from Airbus)

Look, the 737MAX is already overstretching the 60s 737 technology to new ridiculous bounds... but I mean really, it really does look like Boeing has run out of ideas. I mean, look at it: 

737MAX winglets: MD-11 winglets made curvier or
Airbus Wingtip fence bent into a curve?
(image by Boeing & Southwest)

The winglets, it's like an Airbus wingtip fence being hammered till its bent! And then:

Nose blister anyone? (image from Boeing)

Nose blister. Yes, I know it's for the extended nose gear to cater for the MAX's bigger engines, but can't Boeing really engineer a flushed nosegear housing? It looks like a mini A330-200F nosewheel blister on a mini-scale (which befits the smaller size of the 737).

Have both Boeing and Airbus really run out of ideas that they have to start copying each other?

No, I'm just kidding. The MAX's new wingtip is like the MD-11, only made curvier.

Going back to humour, while the A320 NEO is simply an A320 with 737NG winglets, the 737MAX can be basically summed up as a 737 body and wing with:

• MD-11 winglets
• Embraer 170/190 tailcone
• A310 fly-by-wire spoiler system
• A320NEO engine (in form of the CFM Leap-X)
• A330-200F nosewheel housing

Hardcore Airbus and Boeing fans are going to have a hard time throwing bricks at each other with the NEO and the MAX, as one can cynically accuse the other of copying due to lack of imagination. The reality is, both Airbus and Boeing do try to push for the best technologies that can be safely put on an aircraft.  But, the development of the MAX and NEO does prove one thing:

There is more than one way to skin a cat...

albeit there isn't much to pick from!

The marketing department of Boeing and Airbus can claim whatever they like when it comes to which one has the best performance. In reality, users know that both make damn competitive narrowbody aircraft, which shouldn't change with the NEO and MAX. Claim all they like, eventually, the certified performance numbers will be revealed in the FCOM2 for the NEO and FPPM for the MAX. If the 320 (with the newer CFM56-3B or IAE V2500-A5 engines) and 737NG certified flight performance numbers are to go by, the edge of one over the other can be as simple as who sneezed at the wrong time during the negotiation process.

As an MD-11 hater, I however, would instead say, "the MD-11 has come back to haunt the skies of the future, in the shape of the MAX's winglets!" Let's hope that the MAX with the MD-11esque winglets don't have the same performance shortfalls as the initial MD-11s...

The MD-11 winglets didn't prevent the performance shortfalls,
will the MAX winglet do better?

UPDATE: Batavia A320 overrun at BPN 12MAR12

EU Ban exempted carrier Batavia A320 runway excursion

On 19th April, Indonesia's National Transportation Safety Commission has released its recommendations for the Batavia Air A320 PK-YVE overrun at Balikpapan that occurred on 12 March 2012. My summary translation of the finding can be found later in this article (with link to source).

What I find disturbing:

• Batavia Air is an airline that is exempted by the EU Ban imposed on Indonesia.
• Aircraft has had problems with nose wheel steering and brake systems since November 2011.
• This incident is the second runway excursion in recent months.
• Airbus has issued recommendations to Batavia Air on fixing the issue prior to the aircraft flying again.
• Batavia Air did not complete the work outlined in the Airbus recommendation before its next revenue flight.
• The combination of brake servo valves installed in the aircraft did not comply with Airbus Service Bulletin issued.
• A Key personnel holding key holding the Technical Director position at the airline was different from the one specified in the airline's Operations Specification document approved by the DGCA.

Credibility of EU Ban and EU Ban Exemption questioned

The EU Ban Exemption for Batavia has raised questions amongst the industry, and the credibility of the EU Ban and its exemptions in particular. With the country now focusing more on raising the FAA Country Category II status back to Category I, the NTSC investigation into the PK-YVE excursion will certainly raise more questions on how Batavia Air received its exemption from the EU Ban, whilst others such as Lion Air who has put in a great effort into safety improvements (with a lot of help from Boeing and ATR), remain in the ban.

Indonesia now has no problems in admitting that the EU Ban and FAA Country Category II "sentences" were caused by safety deficiencies, but seeing which airlines got on the exemption list and which airline remains on the country blacklist is causing a lot of grievances, including allegation of unfairness and political favouring by the EU. The slap in the face for the EU Ban is Indonesia's decision to literally, "screw the EU Ban and let's focus on getting our FAA rating back to Country Category I", and to work with other countries regulators and safety agencies such as Civil Aviation Safety Australia (CASA), Japan Civil Aviation Bureau (JCAB), and even regulators from individual EU member countries. Work with EASA continues but without looking at the EU Transportation and Energy Commission's work.

I guess the conclusion of the country's new direction in safety improvements and the findings into this serious incident investigation is, "yes, we got problems, we're solving it, but we'll get help from those we can trust, screw your ban!"

Summary of findings: PK-YVE operated BTV2911 from Denpasar to Balikpapan with 2 pilots, 5 flight attendants and 178 passengers (including 1 engineer and 1 pilot not on duty). Aircraft landed on 0327UTC at runway 25 Sepinggan Airport, Balikpapan (BPN/WARL). At around 150 meters before the runway end, aircraft veered to the right and pilot attempted to steer the aircraft back onto the centerline. Aircraft stopped at the stopway beyond the runway 07 threshold, and all 4 wheels of the main landing gears sunk 30-40cm into the asphalt. Airport was reopened with a NOTAM advising that the runway usable length was reduced to 2040 meters. Aircraft evacuation was delayed because the required A320 main landing gear jacks had to be sent from Jakarta. Aircraft was moved onto the apron at 1725UTC on 13MAR, and the reduced usable runway length NOTAM was terminated/revoked. Early investigations have found that PK-YVE has suffered from steering and brake system problems since November 2011.  Aircraft was found to have 2 different sets of brake services: 2 units of new model brake servo valve (p/n C20374000-2) and 2 units of older brake model servo valve (C201033500). Servo valve combination is found to be in Non-compliance to Airbus service bulletin (A320-3201089 revision 3) issues 20 September 1995, which when non-identical brake servo are instaled, mandated operators to use 3 new model servo valves (C20374000-2) and 1 old model servo valve (C20103100, C20103100-1 or C20103500). Early NTSC investigations have found that between the aircraft being moved off the runway and the repairs done by Batavia engineers, poor coordination was shown and is a result of poor understanding of procedures and lack of effectiveness of field key personnel. The person holding the Technical Director position at the time of the incident was different from the person specified in the Operations Specification document approved by the Directorate General of Civil Aviation (issued 18 January 2012). The serious incident is the second runway excursion suffered by PK-YVE in recent months, the first one occured on 7 February 2012 at Sentani Airport, Jayapura (DJJ/WAJJ). The NTSC noted that since the February excursion, Airbus has provided several subsequent checks for PK-YVE to Batavia before the aircraft can be flown again. It appears that Batavia has deemed the problem solved as the aircraft maintenance computers had not reported any faults. Another finding suggests that the engineering personnel may not have understood the pilot report with regards to faults in the brake system. The investigation reveals that Batavia has only partially achieved/completed part of the Airbus recommendations, and the work outlined in the recommendations remained incomplete by the time of the Balikpapan excursion. Summary of recommendations: The NTSC has issued the following recommendations: Batavia Air: To obey and execute recommendations made by the manufacturer on brake and nosewheel steering systems. Improve and ensure the control system on the aircraft configuration remain and continue to comply with the Illustrated Parts Catalogue, Service Bulletins, and recommendations issued. Ensure the status and conditions of the manuals and procedures to be valid and updated and can be accessed by personnel when required, especially in outstations. Balikpapan Airport Review the Emergency Response Plan on handling of incident/serious incident/accident. To cooperate with other agencies and airlines within the airport environment to provide mutual assistance and support in handling incidents/serious incidents/accidents. To include obstacle location and height when issuing NOTAMs. DGCA - Airworthiness Directorate Ensure that Principle Maintenance Inspectors me more aware and understand aircraft repetitive problems. Ensure that Key Personnel duties are carried out by persons specified in the valid Operation Specification Ensure that operators have better control systems over aircraft configuration and manual status. DGCA - Air Navigation Directorate To include obstacle height and position when issuing NOTAMs caused by obstacles, to be used as reference when calculating aircraft operational performance Source: Immediate Safety Recommendations - Serious Incident Airbus A320-231 PK-YVE Balikpapan Sepinggan Airport 12 March 2012 - National Transportation Safety Commission (Rekomendasi Segera Kejadian Serius Pesawat Airbus A320-231 Registrasi PK-YVE Di Bandara Sepinggan, Balikpapan, Tanggal 12 Maret 2012, KNKT/001/3/IV/REK.KU/2012)

Batavia A320 overran at Balikpapan Airport

On Monday 12 March 2012, a Batavia Air Airbus A320-200 PK-YVE peforming Y6-2911 from Denpasar to Hangzhou or Guangzhou (charter flight) via in Balikpapan, landed in Balikpapan and overran the runway at 11:31 local time (03:31 UTC)

It is unclear whether the aircraft was due to make a stop in Balikpapan or had diverted there. The aircraft overran after landing at runway 25. Photos showing the aircraft at the overrun area just beyond the threshold of runway 07 shows the flaps in the up position but cannot be determined if the flaps were retracted after coming to a stop.

Wheels were sunk.

No injuries or damage occured but the airport was closed for at least 2 hours because the aircraft tires had sunk in the softer overrun area asphalt. This was similar to the Lion Air occurence a few months ago, where it overran whilst landing at runway 25 and then was stuck because the wheels had also sunk.

The airport reopened with a NOTAM showing a 400 meter reduced length restriction to allow for obstacle clearance as the aircraft remained in the same position for a few hours.

Photo taken from an aircraft approaching 07 after airport reopened
but prior to removal of the aircraft, making it "interesting".

 All photos were found on the net using. Copyright holders of the photos are unknown.

Follow on Blog Update on the incident can be found HERE